Research shows a connection between students' self-perceptions and academic performance in school. This study determined if there is a relationship between students' ratings on the Piers-Harris Children's Self-Concept Scale, 2nd Edition and their grade point average (GPA), period absences, and performance on California Standardized Tests (CST) in English and math. Data were also analyzed according to gender, ethnicity, and special education placement. Participants included 51 students with mild disabilities at a Southern California high school. Results indicated a positive correlation between GPA and Behavioral Adjustment domain scores. A negative correlation was found between CST math scores and both Total scores and Happiness and Satisfaction scores. CST English scores were negatively correlated with Popularity scores. No differences were found based on gender, ethnicity, or placement; however, scores on the Intellectual and School Status domain were significantly lower than scores on all other domains. Implications for practice and policy are discussed.