Naturalistic Developmental Behavioral Interventions (NDBIs) are evidence-based interventions implemented by the adults in a child's natural environment (e.g., by practitioners in classrooms). The social validity of this body of research may have an impact on the maintenance of practitioner implementation of NDBIs. We conducted a systematic review to evaluate the components (i.e., goals, procedures, and outcomes) and features of social validation assessment practices within studies where researchers trained practitioners to implement an NDBI with young children with disabilities in early childhood classroom contexts. Results of the systematic review indicated that social validity assessment within practitioner-implemented NDBI studies is lacking. Of the 23 studies identified, only 12 studies reported social validity assessment(s). Findings also highlight a lack of comprehensive social validity assessment and frequent use of biased respondents. An in-depth analysis of social validity assessment methods and features, as well as recommendations for the field, is provided.