We investigated the effectiveness of using constant time delay (CTD) with young adults with intellectual disability on their vocabulary acquisition and retention, as well as expository reading comprehension. Four learners, ages 19 to 21 years, from a postsecondary education program for individuals with disabilities participated in the study. During the intervention, instructors used CTD to teach unknown vocabulary embedded in expository texts. In the context of an alternating treatments design, we found that CTD resulted in greater acquisition and retention of the vocabulary knowledge than the control condition. However, the effects of the vocabulary instruction on comprehension of the expository texts were less clear. Implications for practice are provided.