Statistical power for Aim #2b: A Monte Carlo simulation study was conducted to determine power for the latent growth curve models. The population parameter values for data generation and coverage were taken from the parameter estimates of an analysis of prior alcohol treatment outcome studies. We are primarily interested in testing the hypothesis that the slope would be significantly greater than zero. Based on a sample size of 40 across both conditions, we will have power greater than .80 (α<.05) to detect a slope that is statistically different from zero.