We reviewed all school-based experimental studies with individuals 0 to 18 years published in the Journal of Applied Behavior Analysis (JABA) between 1991 and 2005. A total of 142 articles (152 studies) that met review criteria were included. Nearly all (95%) of these experiments provided an operational definition of the independent variable, but only 30% of the studies provided treatment integrity data. Nearly half of studies (45%) were judged to be at high risk for treatment inaccuracies. Treatment integrity data were more likely to be included in studies that used teachers, multiple treatment agents, or both. Although there was a substantial increase in reporting operational definitions of independent variables, results suggest that there was only a modest improvement in reported integrity over the past 30 years of JABA studies. Recommendations for research and practice are discussed.DESCRIPTORS: treatment integrity, child studies, school interventions, applied behavior analysisThe field of applied behavior analysis has always rested on the fundamental principle that the empirical demonstration of measurable changes in behavior must be related to systematic and controlled manipulations in the environment. That is, the observed changes in the dependent variable (behavior) must be attributed to changes in the independent variable (some environmental event). Without this empirical demonstration, a true science of human behavior is an impossibility (Skinner, 1953). Without objective and documented specification of an independent variable as well accurate independent variable application, definitive conclusions regarding the relation between an independent variable and a dependent variable are compromised. The best way to ensure accurate application of the independent variable is to measure the extent to which treatment is implemented as intended.Documentation of independent variable implementation has been discussed in the literature under the rubric of treatment fidelity (Moncher & Prinz, 1991) or treatment integrity Gresham, Gansle, Noell, & Cohen, 1993;Peterson, Homer, & Wonderlich, 1982;Yeaton & Sechrest, 1981). Treatment integrity refers to the degree to which treatments are implemented as planned, designed, or intended and is concerned with the accuracy and consistency with which interventions are implemented We thank Heidi Olson-Tinker, Lisa Dolstra, Veronica McLaughlin, and Mai Van for assistance with the initial preparation of this article. We also are grateful to Michael J. Vance for assistance with data collection.