This article investigates the mechanisms that voluntary environmental program (VEP) participants adopt to reduce pollution. The focus of this article is the 33/50 program, a VEP introduced by the U.S. Environmental Protection Agency in 1991 and discontinued in 1995. The program called for emissions reductions for 17 chemicals reported to the Toxics Release Inventory. Using a sample of approximately 12,000 plants, the relationship between 33/50 program participation and adoption of pollution reduction practices is studied for three time periods, 1991–1995 (program life), 1996–2004, and 2005–2013. These practices include source reduction activities (SRAs) and recycling, recovery, and treatment (RRTs). The major findings are that during the program's life, 33/50 participants showed increased adoption of SRAs and RRTs for both targeted and nontargeted chemicals. However, once the program ended, higher adoption rates persisted for RRTs only, with a shift in emphasis toward treatment over recycling and recovery.