Many studies have shown that when a new or improved treatment becomes available, its diffusion often follows an unpredictable path and its adoption is inconsistent. Two studies in this issue attempted to tease out factors driving the adoption of newly approved drugs. In the lead article, Marcela Horvitz-Lennon, M.D., M.P.H., and colleagues found a “powerful effect of geography” when they examined uptake across the Florida Medicaid program of long-acting injectable risperidone (LAIR), an antipsychotic that received approval in late 2003. An unadjusted analysis of 2004–2006 Medicaid data found that Latino enrollees were significantly less likely than white enrollees) to receive LAIR. However, when the analysis controlled for place of residence, the disparity disappeared. The geographic concentration of Latino Medicaid beneficiaries in a low-adoption area explained the difference, although the authors could only speculate about why such geographic variation existed in a fee-for-service state program where all enrollees are subject to the same policies (page 1171). Researchers who analyzed 2002–2009 data from 21 Veterans Integrated Service Networks (VISNs) nationwide also found substantial geographic variation in timing and speed of adoption of aripiprazole to treat bipolar disorder, an indication for which the drug received FDA approval in 2004. Robert B. Penfold, Ph.D., and colleagues observed that “scientific approval”—publication of positive findings from placebo-controlled trials of the drug before FDA approval—also influenced VISN prescription patterns (page 1178). In Taking Issue, Stephen Goldfinger, M.D., wonders what factors explain the delayed uptake of evidence-based practices (page 1161).