School librarians work with students across their organizations, including those with disabilities such as autism spectrum disorder (ASD). However, little is known about how prepared school librarians are to serve these students. Using a mixed-methods survey, this study sought to explore training school librarians have completed regarding ASD and students with disabilities, as well as the effects of training on librarian confidence and library services. Based on results, librarians who received training through their school district or professional development outside of coursework reported being more confident in supporting students with ASD in the school library.