diff --git a/Userland/Libraries/LibJS/Runtime/CommonPropertyNames.h b/Userland/Libraries/LibJS/Runtime/CommonPropertyNames.h
index f8976b6b06..ac33bcab6c 100644
--- a/Userland/Libraries/LibJS/Runtime/CommonPropertyNames.h
+++ b/Userland/Libraries/LibJS/Runtime/CommonPropertyNames.h
@@ -104,6 +104,8 @@ namespace JS {
     P(count)                                 \
     P(countReset)                            \
     P(create)                                \
+    P(dateFromFields)                        \
+    P(day)                                   \
     P(days)                                  \
     P(debug)                                 \
     P(decodeURI)                             \
@@ -244,6 +246,8 @@ namespace JS {
     P(milliseconds)                          \
     P(min)                                   \
     P(minutes)                               \
+    P(month)                                 \
+    P(monthCode)                             \
     P(months)                                \
     P(multiline)                             \
     P(name)                                  \
@@ -367,6 +371,7 @@ namespace JS {
     P(weeks)                                 \
     P(with)                                  \
     P(writable)                              \
+    P(year)                                  \
     P(years)
 
 struct CommonPropertyNames {
diff --git a/Userland/Libraries/LibJS/Runtime/ErrorTypes.h b/Userland/Libraries/LibJS/Runtime/ErrorTypes.h
index 08d9e6e69a..39e1ce7799 100644
--- a/Userland/Libraries/LibJS/Runtime/ErrorTypes.h
+++ b/Userland/Libraries/LibJS/Runtime/ErrorTypes.h
@@ -172,9 +172,12 @@
     M(TemporalInvalidDurationPropertyValue, "Invalid value for duration property '{}': must be an integer, got {}")                     \
     M(TemporalInvalidEpochNanoseconds, "Invalid epoch nanoseconds value, must be in range -86400 * 10^17 to 86400 * 10^17")             \
     M(TemporalInvalidISODate, "Invalid ISO date")                                                                                       \
+    M(TemporalInvalidMonthCode, "Invalid month code")                                                                                   \
     M(TemporalInvalidPlainDate, "Invalid plain date")                                                                                   \
     M(TemporalInvalidTime, "Invalid time")                                                                                              \
     M(TemporalInvalidTimeZoneName, "Invalid time zone name")                                                                            \
+    M(TemporalMissingRequiredProperty, "Required property {} is missing or undefined")                                                  \
+    M(TemporalPropertyMustBePositiveInteger, "Property must be a positive integer")                                                     \
     M(ThisHasNotBeenInitialized, "|this| has not been initialized")                                                                     \
     M(ThisIsAlreadyInitialized, "|this| is already initialized")                                                                        \
     M(ToObjectNullOrUndefined, "ToObject on null or undefined")                                                                         \
diff --git a/Userland/Libraries/LibJS/Runtime/Temporal/AbstractOperations.cpp b/Userland/Libraries/LibJS/Runtime/Temporal/AbstractOperations.cpp
index ea415d8619..4080da7961 100644
--- a/Userland/Libraries/LibJS/Runtime/Temporal/AbstractOperations.cpp
+++ b/Userland/Libraries/LibJS/Runtime/Temporal/AbstractOperations.cpp
@@ -116,6 +116,20 @@ Value get_option(GlobalObject& global_object, Object& options, String const& pro
     return value;
 }
 
+// 13.6 ToTemporalOverflow ( normalizedOptions ), https://tc39.es/proposal-temporal/#sec-temporal-totemporaloverflow
+Optional<String> to_temporal_overflow(GlobalObject& global_object, Object& normalized_options)
+{
+    auto& vm = global_object.vm();
+
+    // 1. Return ? GetOption(normalizedOptions, "overflow", « String », « "constrain", "reject" », "constrain").
+    auto option = get_option(global_object, normalized_options, "overflow", { OptionType::String }, { "constrain"sv, "reject"sv }, js_string(vm, "constrain"));
+    if (vm.exception())
+        return {};
+
+    VERIFY(option.is_string());
+    return option.as_string().string();
+}
+
 // 13.8 ToTemporalRoundingMode ( normalizedOptions, fallback ), https://tc39.es/proposal-temporal/#sec-temporal-totemporalroundingmode
 Optional<String> to_temporal_rounding_mode(GlobalObject& global_object, Object& normalized_options, String const& fallback)
 {
@@ -232,6 +246,12 @@ Optional<String> to_smallest_temporal_unit(GlobalObject& global_object, Object&
     return smallest_unit;
 }
 
+// 13.29 ConstrainToRange ( x, minimum, maximum ), https://tc39.es/proposal-temporal/#sec-temporal-constraintorange
+double constrain_to_range(double x, double minimum, double maximum)
+{
+    return min(max(x, minimum), maximum);
+}
+
 // 13.32 RoundNumberToIncrement ( x, increment, roundingMode )
 BigInt* round_number_to_increment(GlobalObject& global_object, BigInt const& x, u64 increment, String const& rounding_mode)
 {
@@ -545,4 +565,93 @@ Optional<TemporalTimeZone> parse_temporal_time_zone_string(GlobalObject& global_
     return TemporalTimeZone { .z = false, .offset = offset, .name = name };
 }
 
+// 13.45 ToPositiveIntegerOrInfinity ( argument ), https://tc39.es/proposal-temporal/#sec-temporal-topositiveintegerorinfinity
+double to_positive_integer_or_infinity(GlobalObject& global_object, Value argument)
+{
+    auto& vm = global_object.vm();
+
+    // 1. Let integer be ? ToIntegerOrInfinity(argument).
+    auto integer = argument.to_integer_or_infinity(global_object);
+    if (vm.exception())
+        return {};
+
+    // 2. If integer is -∞𝔽, then
+    if (Value(integer).is_negative_infinity()) {
+        // a. Throw a RangeError exception.
+        vm.throw_exception<RangeError>(global_object, ErrorType::TemporalPropertyMustBePositiveInteger);
+        return {};
+    }
+
+    // 3. If integer ≤ 0, then
+    if (integer <= 0) {
+        // a. Throw a RangeError exception.
+        vm.throw_exception<RangeError>(global_object, ErrorType::TemporalPropertyMustBePositiveInteger);
+        return {};
+    }
+
+    // 4. Return integer.
+    return integer;
+}
+
+// 13.46 PrepareTemporalFields ( fields, fieldNames, requiredFields ), https://tc39.es/proposal-temporal/#sec-temporal-preparetemporalfields
+Object* prepare_temporal_fields(GlobalObject& global_object, Object& fields, Vector<String> field_names, Vector<StringView> required_fields)
+{
+    auto& vm = global_object.vm();
+
+    // 1. Assert: Type(fields) is Object.
+
+    // 2. Let result be ! OrdinaryObjectCreate(%Object.prototype%).
+    auto* result = Object::create(global_object, global_object.object_prototype());
+    VERIFY(result);
+
+    // 3. For each value property of fieldNames, do
+    for (auto& property : field_names) {
+        // a. Let value be ? Get(fields, property).
+        auto value = fields.get(property);
+        if (vm.exception())
+            return {};
+
+        // b. If value is undefined, then
+        if (value.is_undefined()) {
+            // i. If requiredFields contains property, then
+            if (required_fields.contains_slow(property)) {
+                // 1. Throw a TypeError exception.
+                vm.throw_exception<TypeError>(global_object, ErrorType::TemporalMissingRequiredProperty, property);
+                return {};
+            }
+            // ii. If property is in the Property column of Table 13, then
+            // NOTE: The other properties in the table are automatically handled as their default value is undefined
+            if (property.is_one_of("hour", "minute", "second", "millisecond", "microsecond", "nanosecond")) {
+                // 1. Set value to the corresponding Default value of the same row.
+                value = Value(0);
+            }
+        }
+        // c. Else,
+        else {
+            // i. If property is in the Property column of Table 13 and there is a Conversion value in the same row, then
+            // 1. Let Conversion represent the abstract operation named by the Conversion value of the same row.
+            // 2. Set value to ? Conversion(value).
+            if (property.is_one_of("year", "hour", "minute", "second", "millisecond", "microsecond", "nanosecond", "eraYear")) {
+                value = Value(value.to_integer_or_infinity(global_object));
+                if (vm.exception())
+                    return {};
+            } else if (property.is_one_of("month", "day")) {
+                value = Value(to_positive_integer_or_infinity(global_object, value));
+                if (vm.exception())
+                    return {};
+            } else if (property.is_one_of("monthCode", "offset", "era")) {
+                value = value.to_primitive_string(global_object);
+                if (vm.exception())
+                    return {};
+            }
+        }
+
+        // d. Perform ! CreateDataPropertyOrThrow(result, property, value).
+        result->create_data_property_or_throw(property, value);
+    }
+
+    // 4. Return result.
+    return result;
+}
+
 }
diff --git a/Userland/Libraries/LibJS/Runtime/Temporal/AbstractOperations.h b/Userland/Libraries/LibJS/Runtime/Temporal/AbstractOperations.h
index c0479427be..5b32fd5f83 100644
--- a/Userland/Libraries/LibJS/Runtime/Temporal/AbstractOperations.h
+++ b/Userland/Libraries/LibJS/Runtime/Temporal/AbstractOperations.h
@@ -46,6 +46,13 @@ struct TemporalInstant {
     Optional<String> time_zone_offset;
 };
 
+struct TemporalDate {
+    i32 year;
+    i32 month;
+    i32 day;
+    Optional<String> calendar;
+};
+
 struct TemporalTimeZone {
     bool z;
     Optional<String> offset;
@@ -54,14 +61,18 @@ struct TemporalTimeZone {
 
 Object* get_options_object(GlobalObject&, Value options);
 Value get_option(GlobalObject&, Object& options, String const& property, Vector<OptionType> const& types, Vector<StringView> const& values, Value fallback);
+Optional<String> to_temporal_overflow(GlobalObject&, Object& normalized_options);
 Optional<String> to_temporal_rounding_mode(GlobalObject&, Object& normalized_options, String const& fallback);
 u64 to_temporal_rounding_increment(GlobalObject&, Object& normalized_options, Optional<double> dividend, bool inclusive);
 Optional<String> to_smallest_temporal_unit(GlobalObject&, Object& normalized_options, Vector<StringView> const& disallowed_units, Optional<String> fallback);
+double constrain_to_range(double x, double minimum, double maximum);
 BigInt* round_number_to_increment(GlobalObject&, BigInt const&, u64 increment, String const& rounding_mode);
 Optional<ISODateTime> parse_iso_date_time(GlobalObject&, String const& iso_string);
 Optional<TemporalInstant> parse_temporal_instant_string(GlobalObject&, String const& iso_string);
 Optional<String> parse_temporal_calendar_string(GlobalObject&, String const& iso_string);
 Optional<TemporalDuration> parse_temporal_duration_string(GlobalObject&, String const& iso_string);
 Optional<TemporalTimeZone> parse_temporal_time_zone_string(GlobalObject&, String const& iso_string);
+double to_positive_integer_or_infinity(GlobalObject&, Value argument);
+Object* prepare_temporal_fields(GlobalObject&, Object& fields, Vector<String> field_names, Vector<StringView> required_fields);
 
 }
diff --git a/Userland/Libraries/LibJS/Runtime/Temporal/Calendar.cpp b/Userland/Libraries/LibJS/Runtime/Temporal/Calendar.cpp
index 72270e198d..322552102d 100644
--- a/Userland/Libraries/LibJS/Runtime/Temporal/Calendar.cpp
+++ b/Userland/Libraries/LibJS/Runtime/Temporal/Calendar.cpp
@@ -193,4 +193,119 @@ i32 iso_days_in_month(i32 year, i32 month)
     return 28;
 }
 
+// 12.1.36 BuildISOMonthCode ( month ), https://tc39.es/proposal-temporal/#sec-buildisomonthcode
+String build_iso_month_code(i32 month)
+{
+    return String::formatted("M{:02}", month);
+}
+
+// 12.1.37 ResolveISOMonth ( fields ), https://tc39.es/proposal-temporal/#sec-temporal-resolveisomonth
+double resolve_iso_month(GlobalObject& global_object, Object& fields)
+{
+    auto& vm = global_object.vm();
+
+    // 1. Let month be ? Get(fields, "month").
+    auto month = fields.get(vm.names.month);
+    if (vm.exception())
+        return {};
+
+    // 2. Let monthCode be ? Get(fields, "monthCode").
+    auto month_code = fields.get(vm.names.monthCode);
+    if (vm.exception())
+        return {};
+
+    // 3. If monthCode is undefined, then
+    if (month_code.is_undefined()) {
+        // a. If month is undefined, throw a TypeError exception.
+        if (month.is_undefined()) {
+            vm.throw_exception<TypeError>(global_object, ErrorType::TemporalMissingRequiredProperty, vm.names.month.as_string());
+            return {};
+        }
+        // b. Return month.
+        return month.as_double();
+    }
+
+    // 4. Assert: Type(monthCode) is String.
+    VERIFY(month_code.is_string());
+    auto& month_code_string = month_code.as_string().string();
+    // 5. Let monthLength be the length of monthCode.
+    auto month_length = month_code_string.length();
+    // 6. If monthLength is not 3, throw a RangeError exception.
+    if (month_length != 3) {
+        vm.throw_exception<RangeError>(global_object, ErrorType::TemporalInvalidMonthCode);
+        return {};
+    }
+    // 7. Let numberPart be the substring of monthCode from 1.
+    auto number_part = month_code_string.substring(1);
+    // 8. Set numberPart to ! ToIntegerOrInfinity(numberPart).
+    auto number_part_integer = Value(js_string(vm, move(number_part))).to_integer_or_infinity(global_object);
+    // 9. If numberPart < 1 or numberPart > 12, throw a RangeError exception.
+    if (number_part_integer < 1 || number_part_integer > 12) {
+        vm.throw_exception<RangeError>(global_object, ErrorType::TemporalInvalidMonthCode);
+        return {};
+    }
+    // 10. If month is not undefined, and month ≠ numberPart, then
+    if (!month.is_undefined() && month.as_double() != number_part_integer) {
+        // a. Throw a RangeError exception.
+        vm.throw_exception<RangeError>(global_object, ErrorType::TemporalInvalidMonthCode);
+        return {};
+    }
+    // 11. If ! SameValueNonNumeric(monthCode, ! BuildISOMonthCode(numberPart)) is false, then
+    if (month_code_string != build_iso_month_code(number_part_integer)) {
+        // a. Throw a RangeError exception.
+        vm.throw_exception<RangeError>(global_object, ErrorType::TemporalInvalidMonthCode);
+        return {};
+    }
+    // 12. Return numberPart.
+    return number_part_integer;
+}
+
+// 12.1.38 ISODateFromFields ( fields, options ), https://tc39.es/proposal-temporal/#sec-temporal-isodatefromfields
+Optional<TemporalDate> iso_date_from_fields(GlobalObject& global_object, Object& fields, Object& options)
+{
+    auto& vm = global_object.vm();
+
+    // 1. Assert: Type(fields) is Object.
+
+    // 2. Let overflow be ? ToTemporalOverflow(options).
+    auto overflow = to_temporal_overflow(global_object, options);
+    if (vm.exception())
+        return {};
+
+    // 3. Set fields to ? PrepareTemporalFields(fields, « "day", "month", "monthCode", "year" », «»).
+    auto* prepared_fields = prepare_temporal_fields(global_object, fields, { "day", "month", "monthCode", "year" }, {});
+    if (vm.exception())
+        return {};
+
+    // 4. Let year be ? Get(fields, "year").
+    auto year = prepared_fields->get(vm.names.year);
+    if (vm.exception())
+        return {};
+
+    // 5. If year is undefined, throw a TypeError exception.
+    if (year.is_undefined()) {
+        vm.throw_exception<TypeError>(global_object, ErrorType::TemporalMissingRequiredProperty, vm.names.year.as_string());
+        return {};
+    }
+
+    // 6. Let month be ? ResolveISOMonth(fields).
+    auto month = resolve_iso_month(global_object, *prepared_fields);
+    if (vm.exception())
+        return {};
+
+    // 7. Let day be ? Get(fields, "day").
+    auto day = prepared_fields->get(vm.names.day);
+    if (vm.exception())
+        return {};
+
+    // 8. If day is undefined, throw a TypeError exception.
+    if (day.is_undefined()) {
+        vm.throw_exception<TypeError>(global_object, ErrorType::TemporalMissingRequiredProperty, vm.names.day.as_string());
+        return {};
+    }
+
+    // 9. Return ? RegulateISODate(year, month, day, overflow).
+    return regulate_iso_date(global_object, year.as_double(), month, day.as_double(), *overflow);
+}
+
 }
diff --git a/Userland/Libraries/LibJS/Runtime/Temporal/Calendar.h b/Userland/Libraries/LibJS/Runtime/Temporal/Calendar.h
index d729fdba92..1bf37652f2 100644
--- a/Userland/Libraries/LibJS/Runtime/Temporal/Calendar.h
+++ b/Userland/Libraries/LibJS/Runtime/Temporal/Calendar.h
@@ -8,6 +8,7 @@
 #pragma once
 
 #include <LibJS/Runtime/Object.h>
+#include <LibJS/Runtime/Temporal/AbstractOperations.h>
 #include <LibJS/Runtime/Value.h>
 
 namespace JS::Temporal {
@@ -36,5 +37,8 @@ Object* to_temporal_calendar(GlobalObject&, Value);
 Object* to_temporal_calendar_with_iso_default(GlobalObject&, Value);
 bool is_iso_leap_year(i32 year);
 i32 iso_days_in_month(i32 year, i32 month);
+String build_iso_month_code(i32 month);
+double resolve_iso_month(GlobalObject&, Object& fields);
+Optional<TemporalDate> iso_date_from_fields(GlobalObject&, Object& fields, Object& options);
 
 }
diff --git a/Userland/Libraries/LibJS/Runtime/Temporal/CalendarPrototype.cpp b/Userland/Libraries/LibJS/Runtime/Temporal/CalendarPrototype.cpp
index 822c6486d0..756f6ac7d4 100644
--- a/Userland/Libraries/LibJS/Runtime/Temporal/CalendarPrototype.cpp
+++ b/Userland/Libraries/LibJS/Runtime/Temporal/CalendarPrototype.cpp
@@ -5,8 +5,10 @@
  */
 
 #include <LibJS/Runtime/GlobalObject.h>
+#include <LibJS/Runtime/Temporal/AbstractOperations.h>
 #include <LibJS/Runtime/Temporal/Calendar.h>
 #include <LibJS/Runtime/Temporal/CalendarPrototype.h>
+#include <LibJS/Runtime/Temporal/PlainDate.h>
 
 namespace JS::Temporal {
 
@@ -27,6 +29,7 @@ void CalendarPrototype::initialize(GlobalObject& global_object)
 
     u8 attr = Attribute::Writable | Attribute::Configurable;
     define_native_accessor(vm.names.id, id_getter, {}, Attribute::Configurable);
+    define_native_function(vm.names.dateFromFields, date_from_fields, 2, attr);
     define_native_function(vm.names.toString, to_string, 0, attr);
     define_native_function(vm.names.toJSON, to_json, 0, attr);
 }
@@ -54,6 +57,40 @@ JS_DEFINE_NATIVE_FUNCTION(CalendarPrototype::id_getter)
     return js_string(vm, calendar.to_string(global_object));
 }
 
+// 12.4.4 Temporal.Calendar.prototype.dateFromFields ( fields, options ), https://tc39.es/proposal-temporal/#sec-temporal.calendar.prototype.datefromfields
+// NOTE: This is the minimum dateFromFields implementation for engines without ECMA-402.
+JS_DEFINE_NATIVE_FUNCTION(CalendarPrototype::date_from_fields)
+{
+    // 1. Let calendar be the this value.
+    // 2. Perform ? RequireInternalSlot(calendar, [[InitializedTemporalCalendar]]).
+    auto* calendar = typed_this(global_object);
+    if (vm.exception())
+        return {};
+
+    // 3. Assert: calendar.[[Identifier]] is "iso8601".
+    VERIFY(calendar->identifier() == "iso8601"sv);
+
+    // 4. If Type(fields) is not Object, throw a TypeError exception.
+    auto fields = vm.argument(0);
+    if (!fields.is_object()) {
+        vm.throw_exception<TypeError>(global_object, ErrorType::NotAnObject, fields.to_string_without_side_effects());
+        return {};
+    }
+
+    // 5. Set options to ? GetOptionsObject(options).
+    auto* options = get_options_object(global_object, vm.argument(1));
+    if (vm.exception())
+        return {};
+
+    // 6. Let result be ? ISODateFromFields(fields, options).
+    auto result = iso_date_from_fields(global_object, fields.as_object(), *options);
+    if (vm.exception())
+        return {};
+
+    // 7. Return ? CreateTemporalDate(result.[[Year]], result.[[Month]], result.[[Day]], calendar).
+    return create_temporal_date(global_object, result->year, result->month, result->day, *calendar);
+}
+
 // 12.4.23 Temporal.Calendar.prototype.toString ( ), https://tc39.es/proposal-temporal/#sec-temporal.calendar.prototype.tostring
 JS_DEFINE_NATIVE_FUNCTION(CalendarPrototype::to_string)
 {
diff --git a/Userland/Libraries/LibJS/Runtime/Temporal/CalendarPrototype.h b/Userland/Libraries/LibJS/Runtime/Temporal/CalendarPrototype.h
index 80c96fc56b..714d1f9c51 100644
--- a/Userland/Libraries/LibJS/Runtime/Temporal/CalendarPrototype.h
+++ b/Userland/Libraries/LibJS/Runtime/Temporal/CalendarPrototype.h
@@ -20,6 +20,7 @@ public:
 
 private:
     JS_DECLARE_NATIVE_FUNCTION(id_getter);
+    JS_DECLARE_NATIVE_FUNCTION(date_from_fields);
     JS_DECLARE_NATIVE_FUNCTION(to_string);
     JS_DECLARE_NATIVE_FUNCTION(to_json);
 };
diff --git a/Userland/Libraries/LibJS/Runtime/Temporal/PlainDate.cpp b/Userland/Libraries/LibJS/Runtime/Temporal/PlainDate.cpp
index efe78699f8..1b59f6283b 100644
--- a/Userland/Libraries/LibJS/Runtime/Temporal/PlainDate.cpp
+++ b/Userland/Libraries/LibJS/Runtime/Temporal/PlainDate.cpp
@@ -66,6 +66,57 @@ PlainDate* create_temporal_date(GlobalObject& global_object, i32 iso_year, i32 i
     return object;
 }
 
+// 3.5.4 RegulateISODate ( year, month, day, overflow ), https://tc39.es/proposal-temporal/#sec-temporal-regulateisodate
+Optional<TemporalDate> regulate_iso_date(GlobalObject& global_object, double year, double month, double day, String const& overflow)
+{
+    auto& vm = global_object.vm();
+    // 1. Assert: year, month, and day are integers.
+    VERIFY(year == trunc(year) && month == trunc(month) && day == trunc(day));
+    // 2. Assert: overflow is either "constrain" or "reject".
+    // NOTE: Asserted by the VERIFY_NOT_REACHED at the end
+
+    // 3. If overflow is "reject", then
+    if (overflow == "reject"sv) {
+        // IMPLEMENTATION DEFINED: This is an optimization that allows us to treat these doubles as normal integers from this point onwards.
+        // This does not change the exposed behaviour as the call to IsValidISODate will immediately check that these values are valid ISO
+        // values (for years: -273975 - 273975, for months: 1 - 12, for days: 1 - 31) all of which are subsets of this check.
+        if (!AK::is_within_range<i32>(year) || !AK::is_within_range<i32>(month) || !AK::is_within_range<i32>(day)) {
+            vm.throw_exception<RangeError>(global_object, ErrorType::TemporalInvalidPlainDate);
+            return {};
+        }
+        auto y = static_cast<i32>(year);
+        auto m = static_cast<i32>(month);
+        auto d = static_cast<i32>(day);
+        // a. If ! IsValidISODate(year, month, day) is false, throw a RangeError exception.
+        if (is_valid_iso_date(y, m, d)) {
+            vm.throw_exception<RangeError>(global_object, ErrorType::TemporalInvalidPlainDate);
+            return {};
+        }
+        // b. Return the Record { [[Year]]: year, [[Month]]: month, [[Day]]: day }.
+        return TemporalDate { .year = y, .month = m, .day = d, .calendar = {} };
+    }
+    // 4. If overflow is "constrain", then
+    else if (overflow == "constrain"sv) {
+        // IMPLEMENTATION DEFINED: This is an optimization that allows us to treat this double as normal integer from this point onwards. This
+        // does not change the exposed behaviour as the parent's call to CreateTemporalDate will immediately check that this value is a valid
+        // ISO value for years: -273975 - 273975, which is a subset of this check.
+        if (!AK::is_within_range<i32>(year)) {
+            vm.throw_exception<RangeError>(global_object, ErrorType::TemporalInvalidPlainDate);
+            return {};
+        }
+        auto y = static_cast<i32>(year);
+
+        // a. Set month to ! ConstrainToRange(month, 1, 12).
+        month = constrain_to_range(month, 1, 12);
+        // b. Set day to ! ConstrainToRange(day, 1, ! ISODaysInMonth(year, month)).
+        day = constrain_to_range(day, 1, iso_days_in_month(y, month));
+
+        // c. Return the Record { [[Year]]: year, [[Month]]: month, [[Day]]: day }.
+        return TemporalDate { .year = y, .month = static_cast<i32>(month), .day = static_cast<i32>(day), .calendar = {} };
+    }
+    VERIFY_NOT_REACHED();
+}
+
 // 3.5.5 IsValidISODate ( year, month, day ), https://tc39.es/proposal-temporal/#sec-temporal-isvalidisodate
 bool is_valid_iso_date(i32 year, i32 month, i32 day)
 {
diff --git a/Userland/Libraries/LibJS/Runtime/Temporal/PlainDate.h b/Userland/Libraries/LibJS/Runtime/Temporal/PlainDate.h
index fde86d4bd3..1bbae1d0ec 100644
--- a/Userland/Libraries/LibJS/Runtime/Temporal/PlainDate.h
+++ b/Userland/Libraries/LibJS/Runtime/Temporal/PlainDate.h
@@ -6,6 +6,7 @@
 
 #pragma once
 
+#include <LibJS/Runtime/Temporal/AbstractOperations.h>
 #include <LibJS/Runtime/Value.h>
 
 namespace JS::Temporal {
@@ -33,7 +34,8 @@ private:
     Object& m_calendar;    // [[Calendar]]
 };
 
-PlainDate* create_temporal_date(GlobalObject&, i32 iso_year, i32 iso_month, i32 iso_day, Object& calendar, FunctionObject* new_target);
+PlainDate* create_temporal_date(GlobalObject&, i32 iso_year, i32 iso_month, i32 iso_day, Object& calendar, FunctionObject* new_target = nullptr);
+Optional<TemporalDate> regulate_iso_date(GlobalObject&, double year, double month, double day, String const& overflow);
 bool is_valid_iso_date(i32 year, i32 month, i32 day);
 
 }
diff --git a/Userland/Libraries/LibJS/Tests/builtins/Temporal/Calendar/Calendar.prototype.dateFromFields.js b/Userland/Libraries/LibJS/Tests/builtins/Temporal/Calendar/Calendar.prototype.dateFromFields.js
new file mode 100644
index 0000000000..552518d014
--- /dev/null
+++ b/Userland/Libraries/LibJS/Tests/builtins/Temporal/Calendar/Calendar.prototype.dateFromFields.js
@@ -0,0 +1,11 @@
+describe("correct behavior", () => {
+    test("length is 2", () => {
+        expect(Temporal.Calendar.prototype.dateFromFields).toHaveLength(2);
+    });
+
+    test("basic functionality", () => {
+        const calendar = new Temporal.Calendar("iso8601");
+        const date = calendar.dateFromFields({ year: 2000, month: 5, day: 2 });
+        expect(date.calendar).toBe(calendar);
+    });
+});