Three million students in the United States are classified as gifted, yet little is known about the effectiveness of traditional gifted and talented (G&T) programs. In theory, G&T programs might help high-achieving students because they group them with other high achievers and typically offer specially trained teachers and a more advanced curriculum. While previous research indicates that ability grouping is in fact correlated with higher achievement, these findings could be misleading if students placed in high-ability classrooms were likely to be successful for reasons that researchers are unable to measure, such as stronger motivation. To the authors' knowledge, no existing studies offer convincing evidence on the causal effect of G&T programs on student achievement. Their research begins to fill this gap with two studies of the G&T programs available to high-achieving middle-school students in a large urban school district in the southwestern United States. The authors present new evidence on the impact of gifted and talented programs. This article first takes a closer look at the programs and the evidence on their effects. (Contains 3 figures.)