Despite research indicating evidence-based sexual health education results improved student outcomes, students with intellectual and developmental disabilities (I/DD) do not typically receive sexual health education. While school psychologists possess skills that could contribute to sexual health education for students with I/DD, there is no existing research on this topic. To address this, we conducted a survey of school psychologists in a state in the Southeastern United States regarding their attitudes, perceptions of social norm and self-efficacy, and training and familiarity in regard to sexual health education for students with I/DD. The survey's focus and design were guided by the Reasoned Action Approach. Data collection and analyzes addressed (a) the underlying structure and internal consistency of our survey's scales; (b) school psychologists' level of training, knowledge, and beliefs about implementing sexual health education programs with students with I/DD; and (c) the relationship between school psychologists' previous training, knowledge, and beliefs and their implementation of and advocacy for sexual health education for students with I/DD. Descriptive statistics, principal component analyzes, and multiple regression were used to summarize the data and address the research questions. Data from the multiple regression analysis indicated that a significant amount of the variance in participants' implementation/advocacy scores was explained by attitude, social norms, behavioral control/self-efficacy, and training/familiarity. Our findings suggest that school psychologists' engagement in implementation of and advocacy for sexual health education for students with I/DD can be influenced by level of training and knowledge and perceived capability and behavioral control.