College students with autism may be negatively impacted by lack of understanding about autism on college campuses. Thus, we developed an online training to improve knowledge and decrease stigma associated with autism among college students. Participants (N = 365) completed a pre-test, online training, and post-test. Women reported lower stigma towards autism than men. Participation in the training was associated with decreased stigma and increased knowledge about autism. Although participants exhibited relatively high baseline knowledge of autism, misconceptions were common, particularly in open-ended responses. Participants commonly confused autism with other disorders, such as learning disabilities. This study suggests that online training may be a cost-effective way to increase college students' understanding and acceptance of their peers with autism.