You can take attendance for a given schedule date of a Program by going to that Program and clicking on the Attendance tab. Select the Take Attendance link to the right of the date you want to take attendance for. There will then be a two column list. On the left will be all registered members of the program. Click the Add button to mark them as attended and move them to the Attendees column. Clicking the Remove button will take them off the Attendees list and place them back into the Eligible Registrants list.