>For example, gomonth(SomeDate, -100*12) will subtract 100 years. VFP does all the required calculations.

Yes, I think I would use it. I don't think I will have a problem with 2/29 and for all other dates gomonth will return the exact same date 100 years less.

Here is my code

*---------------------- Location Section ------------------------
*   Library: 	Acustomcontrols.vcx
*   Class: 		TxtDOB
*   Method: 	Valid()
*----------------------- Usage Section --------------------------
*)  Description:
*)

*   Scope:      Public
*   Parameters:
*$  Usage:
*$
*   Returns:
*--------------------- Maintenance Section ----------------------
*   Change Log:
*       CREATED 	04/19/2005 - NN
*		MODIFIED    04/20/2005 - NN
*----------------------------------------------------------------
local llReturn, lcYear, lnYear
if this.lValidationCancelled
	llReturn = .t.
	this.lValidationCancelled = .f.
else
	llReturn = not empty(dodefault())
	if m.llReturn
		lcYear = alltrim(substr(this.text,rat('/',this.text)+1,4))
		if len(m.lcYear)<3 and val(m.lcYear) = year(date())%100 && Same year typed as 2 digits
			this.value = iif(this.value > date(), gomonth(this.value, - 100*12),
		endif
		if this.value > date()
			llReturn = .f.
			=ErrorMsg ("Date of birth could not be greater than today's day!")
		endif
	endif
endif

return m.llReturn

and I set nCentury and nRollover properties in the Property sheet.