All teaching and most administrative staff receive Head Start training, even though Head Start pays for only a portion of staff salaries (see below) and teachers work with both Head Start and non-Head Start children. Head Start training and technical assistance funding pays for much of the training, and the SPS program also provides an incentive grant for staff training. Staff participate in four categories of training: pre-service, orientation, in-service workshops, and in-service conferences. Some training is done on Saturdays, including two annual conferences for the full staff, but most training is conducted during the week during children's naptime, when center supervisors (who also are credentialed teachers) step in to relieve staff in training. Staff receive two weeks of paid leave in July. They also receive additional paid compensatory leave at the December holidays, up to the number of hours of Saturday training in which they have participated.