diff --git a/src/Morphir/SDK/LocalDate.elm b/src/Morphir/SDK/LocalDate.elm
index e377aeb15..9e57ac5ef 100644
--- a/src/Morphir/SDK/LocalDate.elm
+++ b/src/Morphir/SDK/LocalDate.elm
@@ -19,7 +19,7 @@ module Morphir.SDK.LocalDate exposing
     ( LocalDate
     , diffInDays, diffInWeeks, diffInMonths, diffInYears
     , addDays, addWeeks, addMonths, addYears
-    , toISOString, fromISO, fromParts
+    , toISOString, fromCalendarDate, fromISO, fromOrdinalDate, fromParts, fromRataDie, toRataDie
     , DayOfWeek(..), dayOfWeek, isWeekend, isWeekday
     , Month(..)
     , year, month, day
@@ -41,8 +41,10 @@ module Morphir.SDK.LocalDate exposing
 
 # Constructors
 
-@docs toISOString, fromISO, fromParts
+@docs fromCalendarDate, fromISO, fromOrdinalDate, fromParts, fromRataDie
 
+# Convert
+@docs toISOString, toRataDie
 
 # Query
 
@@ -50,6 +52,8 @@ module Morphir.SDK.LocalDate exposing
 @docs Month
 @docs year, month, day
 
+
+@docs toISOString
 -}
 
 import Date exposing (Date, Unit(..))
@@ -117,6 +121,24 @@ addYears : Int -> LocalDate -> LocalDate
 addYears count date =
     Date.add Years count date
 
+{-| Create a date from a [calendar date][gregorian]: a year, month, and day of
+the month. Out-of-range day values will be clamped.
+
+    import Date exposing (fromCalendarDate)
+    import Time exposing (Month(..))
+
+    fromCalendarDate 2018 Sep 26
+
+[gregorian]: https://en.wikipedia.org/wiki/Proleptic_Gregorian_calendar
+
+-}
+fromCalendarDate : Int -> Month -> Int -> LocalDate
+fromCalendarDate y m d =
+    Date.fromCalendarDate y (monthToMonth m) d
+
+fromOrdinalDate : Int -> Int -> LocalDate
+fromOrdinalDate y d =
+    Date.fromOrdinalDate y d
 
 {-| Construct a LocalDate based on ISO formatted string. Opportunity for error denoted by Maybe return type.
 -}
@@ -213,6 +235,44 @@ month localDate =
         Time.Dec ->
             December
 
+monthToMonth : Month -> Time.Month
+monthToMonth m =
+    case m of
+        January ->
+            Time.Jan
+
+        February ->
+            Time.Feb
+
+        March ->
+            Time.Mar
+
+        April ->
+            Time.Apr
+
+        May ->
+            Time.May
+
+        June ->
+            Time.Jun
+
+        July ->
+            Time.Jul
+
+        August ->
+            Time.Aug
+
+        September ->
+            Time.Sep
+
+        October ->
+            Time.Oct
+
+        November ->
+            Time.Nov
+
+        December ->
+            Time.Dec
 
 {-| The day of the month (1–31).
 -}
@@ -297,3 +357,18 @@ type Month
     | October
     | November
     | December
+
+{-| Construct a LocalDate from Integer Rata Die, a system for system for assigning calendar days to
+numbers, with 1 representing 0001-01-01.
+-}
+fromRataDie : Int -> LocalDate
+fromRataDie rataDieNumber =
+    Date.fromRataDie rataDieNumber
+
+
+{-| Convert a LocalDate to its number representation in Rata Die.  Rata Die is a system for
+assigning calendar days to numbers, with 1 representing 0001-01-01.
+-}
+toRataDie : LocalDate -> Int
+toRataDie localDate =
+    Date.toRataDie localDate
diff --git a/tests/Morphir/SDK/LocalDateTests.elm b/tests/Morphir/SDK/LocalDateTests.elm
index 220c37fd0..89ae364c6 100644
--- a/tests/Morphir/SDK/LocalDateTests.elm
+++ b/tests/Morphir/SDK/LocalDateTests.elm
@@ -96,4 +96,29 @@ constructorTests =
             \_ ->
                 LocalDate.fromParts 2020 2 30
                     |> Expect.equal Nothing
+        , test "valid fromCalendarDate" <|
+            \_ ->
+                LocalDate.fromCalendarDate 2023 December 25
+                    |> Expect.equal (Date.fromCalendarDate 2023 Dec 25)
+        , test "invalid but pinned fromCalendarDate" <|
+            \_ ->
+                LocalDate.fromCalendarDate 2023 December 39
+                    |> Expect.equal (Date.fromCalendarDate 2023 Dec 31)
+        , test "valid fromRataDie" <|
+            \_ ->
+                LocalDate.fromRataDie 1
+                    |> Expect.equal (Date.fromCalendarDate 1 Jan 1)
+        , test "valid contemporary fromRataDie" <|
+            \_ ->
+                LocalDate.fromRataDie 738860
+                    |> Expect.equal (Date.fromCalendarDate 2023 Dec 6)
+        , test "valid toRataDie" <|
+            \_ ->
+                Date.fromCalendarDate 1 Jan 1
+                    |> LocalDate.toRataDie
+                    |> Expect.equal 1
+        , test "valid contemporary toRataDie" <|
+            \_ ->
+                LocalDate.toRataDie (Date.fromCalendarDate 2023 Dec 6)
+                    |> Expect.equal 738860
         ]