Research shows that preadolescent females are more prone to negative self-perceptions than their male counterparts which places them at greater risk of developing mental health problems stemming from low self-image. The purpose of this randomized, controlled outcome study was to examine the effectiveness of group activity play therapy (GAPT) compared to an evidenced based social skills/self-esteem group. Participants were 29 fourth and fifth grade girls in two Title I schools in the southwest U.S. referred by teachers and school counselors as presenting with low self-esteem. Participants identified as 45% Latina, 38% Caucasian, 14% African American, and 3% Asian. Children were randomly assigned to either 16 sessions of GAPT (experimental group; n = 15) or 13 sessions of an evidenced based social skills/self-esteem group intervention (control group; n = 14). Results from a 2 (Group) by 3 (Times) repeated measures ANOVA indicated that, compared to the control group over time, the GAPT group reported statistically significant improvement in self-esteem with a moderate to large treatment effect. Teachers did not report a statistically significant difference between the two groups over time. However, teachers reported noteworthy improvement for children in both treatment groups, with generally stronger improvement for the GAPT group. Overall, results indicate that GAPT may be a promising school-based intervention for preadolescent females suffering with low self-esteem.