Recognizing that welfare recipients who find jobs may remain poor, the "make work pay" approach rewards those who work by boosting their income. This strategy was the centerpiece of the Self-Sufficiency Project (SSP), a large-scale demonstration program in Canada that offered monthly earnings supplements to single parents who left welfare for full-time work. Launched in 1992, SSP was evaluated by MDRC in collaboration with the Social Research and Demonstration Corporation. As detailed in this report, which examines the program's effects on welfare recipients over five years, SSP substantially increased full-time employment, earnings, and income and reduced the poverty rate - all at a low net cost to the government. The program also improved the school performance of enrollees' elementary school-aged children, a benefit that - unlike the positive economic effects - persisted even after parents stopped receiving the supplement.