Using data from an evaluation of two welfare-to-work programs in Riverside, California, and Grand Rapids, Michigan, a study found that requirements to participate in mandatory welfare-to-work programs can increase employment and earnings and reduce welfare income, independent of actual participation in the welfare-to-work program. Usually, these independent effects of the participation were not captured by estimates of welfare-to-work program impacts, because program impacts were measured conditional on the actual showing up of those required to participate. Outcomes for two groups were compared: one required to show up for a welfare-to-work program orientation but subsequently excused from participation in welfare-to-work program activities and another control group that was not required to show up for the initial orientation. Analyses found larger effects of the mandate for welfare recipients who were more job-ready and for programs operating in healthier labor markets. Evidence also indicated that response to a mandate increased with the strength of the enforcement and the level of penalties for noncompliance. (Contains 13 references.) (YLB)