School counselors are often the first professionals to become aware of the mental health problems of young children. Given that play therapy is the most developmentally appropriate approach for elementary school-age children, it is important to understand why some school counselors use play therapy and others do not. The purpose of this study was to address this question by examining variables related to elementary school counselors’ use or nonuse of play therapy in the elementary school setting. A survey was sent to a random sample of elementary school counselors who were members of the American School Counselor Association. The findings indicated that perceived effectiveness was a significant predictor of the use of play therapy among elementary school counselors. The implications of the findings include the value of the newly formed School Based Registered Play Therapist credential to address issues of effectiveness and supervision of school counselors and their use of play therapy. © 2018 Association for Play Therapy.