Twenty-four children (ages 27-58 months) with autism were tested on the Bayley, Merrill-Palmer, and Vineland scales. While scores on the different tests were highly correlated, actual test scores varied considerably, with the Bayley tending to produce the lowest IQ scores and the Merrill-Palmer the highest. Implications for selecting pre- and post-treatment measures are considered. (Contains references.) (Author/DB)