The purpose of this study was to assess the degree to which behavioral intervention studies conducted with persons with mental retardation operationally defined the independent variables and evaluated and reported measures of treatment integrity. The study expands the previous work in this area reported by Gresham, Gansle, and Noell (1993) and Wheeler, Baggett, Fox, and Blevins (2006) by providing an evaluation of empirical investigations published in multiple journals in the fields of applied behavior analysis and mental retardation from 1996-2006. Results of the review indicated that relatively few of the studies fully reported data on treatment integrity. (Contains 5 figures and 2 tables.)