Diagnoses of autism spectrum disorders (ASDs) have been on the rise, and the need for knowledgeable and competent professionals is dire. However, few social workers enter the field of ASDs. Rooted in social cognitive theory, this study examined the extent to which knowledge, interest, contact, and training predicted master's in social work students' self-efficacy in working with individuals with ASDs. Approximately 18% of the variance was explained (R(2) = .18, p < .001), with knowledge and contact predicting a significant proportion of the variance. Implications for social work practice and education are discussed.