Since S. C. Bratton and G. L. Landreth published the first Child-Parent Relationship Therapy (CPRT) outcome study in 1995, the evidentiary base for CPRT has grown as studies’ methodological rigor increased. CPRT is one of the more well-researched treatment protocols in the field of play therapy and in the broader area of child therapy practices. The considerable body of CPRT research rests firmly on the empirical foundation laid by the Guerneys and their colleagues in the 1960s and 1970s. Important happenings include the national recognition of CPRT as an evidence-based practice by the National Registry of Evidence-based Programs and Practices and by the California Evidence-Based Clearinghouse for Child Welfare. The strongest CPRT finding is its effectiveness with adoptive families. The effectiveness of CPRT with diverse populations is strength of the treatment model. CPRT’s transportability is demonstrated by its successful use in a variety of real-world settings, including community agencies, churches, public and private schools, shelters, prisons/county jails, and hospitals.