Abstract: A regimen calendar is provided which permits the correlating of time periods of a predetermined regimen with the calendar time periods in which such regimen is being performed. The calendar has a plurality of first pages or other media on which information concerning the regimen for a given time period may be recorded and a plurality of second sequentially arranged pages or other media containing indicia of selected calendar time periods. The first and second pages are mounted such that one of the first pages and one of the second pages are being displayed, and that the first and second pages may be independently changed so that any first page may be displayed with any second page. More of the second pages are provided than the first pages, permitting the regimen to commence at a calendar time period later than the earliest calendar time period for which there is a second page, with correlation between the first and second pages still being possible for the regimen time periods represented by the first pages.