Young, severely maladaptive autistic children with some speech competence were compared to normally developing three-year-old children of lower and middle class and five-year-old children of lower class on negation tasks. All subjects were shown twelve sets of cards depicting negative contrasts designed to elicit semantic categories of nonexistence, denial, and rejection, and were tested for production, imitation, and comprehension. Syntactic and semantic analysis revealed that autistic children were superior imitators and poor producers but showed skills in comprehension comparable to a four-year-old's level of functioning. While retarded in some functions, the experimental group produced syntactic structures that were more rigid, suggesting the significantly greater use of imitation as a major strategy in linguistic coding.