Anxiety and autism spectrum disorder (ASD) commonly co-occur, but school-based assessment practices surrounding identification of co-occurring presentations are not well understood. This study examined school psychologists' assessment practices for anxiety in students with ASD, perceptions of their role in the assessment process, and perceived training needs. Participants were a national sample of 177 practicing school psychologists who completed a mail-based questionnaire developed for the study. Most participants agreed that assessment for symptoms of anxiety in students with ASD was part of their role. Assessment practices were similar across school psychologists with varying levels of experience and between doctoral and non-doctoral school psychologists. Common assessment practices were identified, and most participants indicated a need for more training. Implications for future research and practice are discussed.