This study examined relationships between instructor autonomy support, academic self-efficacy, academic problems and academic achievement among student service members/veterans (SSM/V). Participants included veterans, active duty or National Guard/Reservists of the US military (N = 172) enrolled in a postsecondary institution. Online surveys generated responses to indicators of instructor autonomy support, academic self-efficacy, and academic problems. Grade point average (GPA) was obtained from the institution. Multiple regression models found that academic self-efficacy and academic problems independently predicted GPA. Health-related factors (e.g. depression) explained academic self-efficacy, academic problems and academic achievement. Academic self-efficacy and academic problems independently mediated the relationship between instructor autonomy support and GPA. Results indicate that greater academic self-efficacy, fewer academic problems and an autonomy-supportive education environment may promote academic achievement in SSM/V despite the presence of health-related factors such as depression, posttraumatic stress and mild traumatic brain injury. Supported education programs may further academic achievement among SSM/V.