This paper explores the dynamics of rBST adoption using panel data from Wisconsin dairy farmers that span the period from its commercial introduction in 1994 to 2001. The panel data allow an examination of a broader range of adoption behavior that includes disadoption, early and late adoption, as well as persistent non-adoption. The data also permit attention to endogeneity concerns that arise in cross-sectional analyses of technology adoption, where potential predictors are also choice variables. Differences in both complementary technology use and farm size are identified as key predictors of adoption behavior, as are farmer attitudes toward this controversial technology.