This paper critiques and summarizes the literature on how the economy, policy, and other factors contributed to falling welfare caseloads during the 1990s. There is broad agreement that economic growth contributed importantly to this decline but less unanimity on the role of policy. Some researchers conclude that welfare reform contributed nearly as much to reduced dependency as the economy, while others find little influence. The author identifies additional research that, if undertaken soon, would help to decide this critical question as Congress debates TANF reauthorization.