This study was designed to determine the effectiveness of individual child-centered play therapy in the elementary school in: 1) enhancing the self-concept of kindergarten children who are experiencing adjustment difficulties; 2) decreasing the overall behavioral problems of kindergarten children experiencing adjustment difficulties 3) decreasing externalizing behavior problems such as aggression and delinquency of kindergarten children experiencing adjustment difficulties; 4) decreasing the internalizing behavior problems such as withdrawal, somatic complaints, anxiety and depression of kindergarten children experiencing adjustment difficulties; 5) increasing parental perception of change in the problematic behaviors of kindergarten children experiencing adjustment difficulties; and 6) enhancing self-control in kindergarten children experiencing adjustment difficulties. A secondary objective was to compare the participants involved in individual child-centered play therapy with participants in a previous study who were involved in child-centered group play therapy on the above named dimensions. The experimental group, consisting of 14 kindergarten children experiencing adjustment difficulties, received 10-12, 30-minute individual play therapy sessions in a 12 week period in their elementary school. The comparison group, utilized from the 1999 McGuire study, consisted of 15 children with adjustment problems and received 12-14, 45-minute group play therapy sessions in 14 weeks in their elementary school. The control group, consisting of 13 children experiencing adjustment problems, received no play therapy intervention over a 12 week period. An Analysis of Covariance revealed significant findings in 1 of the 6 hypotheses and one subscale hypothesis examining the effectiveness of individual play therapy versus the wait list control group. Specifically, children with adjustment problems in the experimental group exhibited a significant reduction in total behavior problems and a significant reduction in externalizing behavior problems as measured by the Child Behavior Checklist-Parent Form (CBCL). Additionally, an Analysis of Covariance revealed significant findings in 1 of the 6 hypotheses examining the comparison of the effectiveness of individual play therapy versus the group play therapy comparison group from McGuire (1999). Individual play therapy was significantly more effective than group play therapy in helping children maintain an acceptable level of classroom behaviors as perceived by teachers on the Early Childhood Behavior Scale (ECBS).