Treatment implementation is an under-studied and under-reported aspect of intervention studies involving individuals with autism spectrum disorder (ASD). One primary area of concern is the lack of reliable and valid implementation measures, which allows a conclusive association to be drawn between the intervention and participant outcomes. This study examined the psychometric properties of two implementation measures developed for comprehensive treatment models serving preschoolers with ASD (i.e., LEAP and TEACCH). Both of the measures were completed in classrooms using LEAP or TEACCH instructional approaches as well as in classrooms in which a business-as-usual or nonmodel specific treatment approach was used. Across four months of one school year, a maximum of 4 observations were conducted in each of the 34 classrooms involved in the study. Results indicated that both implementation tools are reliable and valid, and that particular subscales of these measures allowed for discrimination of the three types of classrooms from each other. This step of psychometrically validating implementation measures as part of conducting efficacy studies may yield more robust associations between implementation and intervention effects