This study compares the effectiveness and efficiency of constant time delay (CTD) and simultaneous prompting (SP) to teach decoding and word reading to four students, 7 to 9 years of age, with intellectual disabilities (ID) in the mild to moderate range. An adapted alternating treatment design was implemented to assess the two methods. The results suggest that both procedures were equally effective. All four students learned to decode and read the instructional words. Maintenance data showed no substantial differences between the two teaching procedures. CTD was more efficient according to two efficiency measures since three students acquired the word sets taught with CTD in fewer sessions and trials. However, SP was more efficient in terms of the number and percentage of errors made and the instructional time needed for all four students. Two students were able to decode and read all or some of the generalization words, while the other two were able to decode a higher percentage of sounds within the words than before the teaching sessions. This study shows that CTD and SP are effective in improving reading skills for students with ID.