Individuals with disabilities are underrepresented in science, technology, engineering, and math (STEM) fields. The purpose of this study was to experimentally evaluate the impact of a STEM mentor intervention and differences between students matched with mentors with or without disabilities on career planning outcomes. An independent groups × repeated measures design was used. Significant differences were found between mentored and nonmentored students for measures of STEM-related knowledge, engagement, confidence, and general career planning confidence, but not for STEM-related and disability-related self-efficacy. Significant differences were not found between students assigned to mentors with or without disabilities. This study contributes to research that demonstrates the positive impact of mentoring on career planning for students with disabilities, including those related to STEM.