The No Child Left Behind (NCLB) legislation has created pressure for districts to improve their students' proficiency levels on state tests. Districts that fail to meet their academic targets for 3 years must use their Title I funds to pay for supplemental education services (SES) that provide tutoring or other academic instruction. Many districts, including the Pittsburgh Public Schools (PPS), have also adopted additional tutoring programs designed to help students reach proficiency goals. This paper examines student participation and achievement in two PPS tutoring programs--the NCLB-mandated SES program and a state-developed tutoring program. We examine the characteristics of students participating in each program, the effects of participation on student achievement, and the program features that are associated with improved achievement.