An adapted alternating-treatments design was used to compare the effectiveness and efficiency of constant time delay and simultaneous prompting procedures within an embedded instruction format on the acquisition of various leisure skills by four preschool students with autism. The results showed that both procedures were effective in promoting the acquisition of the skills and maintaining them over time by three students. Although the impacts of the procedures were evident for these three students, the results were not replicated with the fourth student. Furthermore, mixed results were obtained regarding the efficiency measures. However, the social validity findings of the study were positive overall. On the basis of an evaluation of the findings, implications and future research needs are discussed. (Contains 3 tables and 4 figures.)