A continuous memorizing situation was studied in which test and study trials alternated throughout an experimental session. The items studied were paired-associates. The interval between study and test for a particular item was randomly determined; and an item was given one, two, three or four reinforcements. A quantitative model is proposed which has two memory stores: a short-term store in which the subject generates a carefully controlled rehearsal scheme of fixed length, and a long-term store in which information is accumulated and lost. A large number of theoretical predictions of the model were verified quantitatively by the data, which confirm results of previous experiments, and support the hypothesis that highly structured rehearsal schemes play a major role in many short-term memory and learning situations.