Constant time delay (CTD) and simultaneous prompting (SP) are effective response prompting procedures for teaching students with moderate to severe disabilities. The purpose of this study was to compare the efficiency of CTD and SP when teaching functional sight words to four students, 8-11 years of age, with moderate intellectual disability (ID) or dual diagnosis of moderate ID and autism spectrum disorder. An adapted alternating treatments design was used to evaluate the efficiency of CTD and SP procedures in regard to (a) percent of training errors, (b) total number of sessions, (c) mean minutes of training time, and (d) total number of trials through criterion. Results indicated that CTD resulted in fewer errors and SP required less instructional time, with mixed results for number of sessions and trials through criterion.