The spacing effect refers to the commonly observed phenomenon that memory for spaced repetitions is better than for massed repetitions. In the present study, we examined this effect in students' memory for a lengthy expository text. Participants read the text twice, either in immediate succession (massed repetition), with a 4-day interstudy interval (spaced short), or with a 3.5-weeks interstudy interval (spaced long). Two days after the second study trial, all participants were tested. The results demonstrated that students in the spaced-short condition remembered more of the content than those in the massed condition. By contrast, students in the spaced-long condition remembered as much as students in the massed condition. These results were interpreted in terms of a theoretical framework, which combines mechanisms of encoding variability and study-phase retrieval to account for the spacing effect. Copyright © 2007 John Wiley & Sons, Ltd.