The preventive parent training program Stepping Stones Triple P (SSTP) (Sanders et al., 2004a), which was originally developed in Australia, is currently being examined in German-speaking countries. The object of this paper is to review the actual status of research on the validity of the SSTP program. Within this context, aspects of theoretical, internal and external (social) validity are examined. Based on two controlled-randomized primary studies on the effectiveness of SSTP, a secondary analysis was carried out in order to calculate effect sizes. The findings indicate (a) a positive internal validity, shown by replicated substantial and stable effects of the program onto child problem behavior as well as parental behavior; (b) a generally positive theoretical validity which has however certain restrictions regarding the shaping of the timeout component as well as the role of operant methods, and (c) a generally positive external validity which has however certain restrictions, in particular regarding the controversial social evaluation of the time-out component. From the results conclusions were drawn for a selective adaptation of the program as well as implementing SSTP as a preventive intervention method in families with children with developmental disabilities in German-language regions in the future.