We surveyed 439 professionals in the field of autism to assess their knowledge and perceptions about fragile X syndrome (FXS) and related issues. Almost half had worked with at least one child diagnosed with FXS, yet most lacked basic knowledge about the condition, underestimated its significance in the etiology of autism spectrum disorders, and rarely accessed fragile X–specific resources. A majority perceived etiology to be an important variable in therapeutic response while three quarters felt that professionals in the field of autism should play an active role in referring children for etiological evaluation. Despite these opinions, most respondents either rarely or never inquired about etiology when working with a new client. The survey results underscore the need for training and education so that autism professionals can become effective partners in diagnostic genetic referral and in research and implementation of syndrome-specific interventions.