Early identification of autism is important in order to maximize the potential of intervention efforts. However, the identification of autism can require extensive training and experience. Psychologists routinely use behavior rating scales to assess children for various social, emotional, or behavioral problems when completing evaluations in the school or clinical setting. The focus of the current study is to determine whether a behavior rating scale can accurately distinguish between referred preschoolers with autism and referred preschoolers without autism. Parents of 82 preschoolers referred to a nonprofit child development clinic because of behavioral or developmental concerns completed two behavior rating scales as part of the initial evaluation. The findings revealed that while statistically significantly differences were found between the scores for the two groups on a number of scales, the practical implications were unclear. The use of behavior rating scales as screeners for autism in preschoolers would result in a very high false positive rate.