The purpose of this study was to determine the effectiveness of co-teaching versus inclusive non-co-teaching for students with disabilities (SWD) using algebra I end-of-course scores (EOC) and whether these effects differed by gender. Participants included 244 ninth-grade algebra I SWD. The research design consisted of a posttest only with a control group and a test group. Analysis of covariance (ANCOVA) was used to analyze the results. Results showed that co-teaching did not significantly benefit either male or female SWD in algebra I. The fact that SWD in inclusive settings who did not receive co-teaching scored higher than those in inclusive settings who did receive co-teaching is significant and has important implications for practice and research. Future research should investigate studies with larger sample size and proficiency of teachers in co-taught classes.