I want to use DatePicker to select dates from Before the Common Era (BCE) all the way to future dates. When I select a date in DatePicker and extract the DateComponents for dates prior to the adoption of the Gregorian Calendar, the month and day appear to be more consistent with the old Julian Calendar. This is not what I expected ... the documentation states that if Gregorian is specified as the calendar, a "proleptic" Gregorian Calendar will be assumed. This does NOT appear to be the case. The docs also state that "ten days were removed from the Gregorian Calendar". I understand the differences between the old Julian Calendar and the Gregorian ... but for instance, when I select "3/10/1500" on the DatePicker and extract the DateComponents, the MONTH is shown as "2" and the day as "29". In a Julian Calendar that makes sense ... but in a proleptic Gregorian calendar, I should never be able to have a Feb 29, 1500: That is NOT a leap year in the Gregorian calendar. I'm missing something ... the inconsistencies exactly match the differences specified in a Wikipedia article on conversions between Julian and Gregorian dates. But that's NOT a proleptic Gregorian Calendar, it's more like an automatic conversion from Gregorian (from the DatePicker) to Julian (as shown in the extracted DateComponents). HELP!