The revival of interest in the effectiveness of spaced practice, as compared with massed practice, in learning is attributed to the abandonment of the constraints of serial and pairedassociate list learning and the discovery of stable benefits from spaced practice in continuous paired-associate learning, short-term memory for individual items, and single-trial free-recall learning. Comments are made about the preceding symposium papers by Underwood, Waugh, and Greeno,,and some data on the differential effects of spacing of repetitions in freerecall learning are introduced in an effort to assess the current state of fact and theory.Before looking at the data and theories that have been presented at this symposium, it seems to me worthwhile to consider how we have gotten to where we are today in the examination of the question of the relative effectiveness of massed practice (MP) and distributed practice (DP), and why.