The emergence of equivalence relations and the role of overall verbal competence and stimulus nameability and familiarity in this regard were investigated across 3 experiments involving 15 children diagnosed with autistic spectrum disorder (ASD), as well as 3 typically developing children. The experimental sequence comprised 4 identical stages, each with 4 phases. The relationship between verbal competence and equivalence was assessed by including children with ASD categorized with different levels of verbal behavior. Stimulus nameability and familiarity were assessed by systematically varying these features across different stimulus sets presented during 4 experimental stages. The results of all experiments indicated that the equivalence performances of both groups were influenced by their levels of verbal behavior and to some extent by stimulus familiarity. The data are discussed in the context of alternative theoretical accounts of the processes believed to underlie equivalence. (Contains 11 tables.)