Allied health professionals (AHPs) are trusted sources of information and intervention for clients with autism spectrum disorder. However, the level of implementation of empirically-supported therapies and the accuracy of the knowledge they use to inform intervention selection is largely unknown. The present study explored the accuracy of AHPs' knowledge and use of practices, and explored links to individual attitudes and organisational culture. Overall results from the 156 AHPs surveyed suggested general accuracy of knowledge, and use of empirically supported treatments, with accuracy linked to use. Use of practices unsupported by research was linked to organisational culture and openness to new interventions. The presence of misinformation and the impact on selection and use of effective practices are discussed.