The development of an inventory to measure self-regulated learning is reported. The first step involved the generation of an item pool based on a literature review. A pool of items was developed based on the five identified factors of metacognition, learning strategies, motivation, contextual sensitivity, and environmental utilization and control. A pilot version with 71 items was tested with 305 undergraduates, and one factor, self-regulated learning, was found to account for the largest portion of the variance. In the second version of the inventory, researchers began to construct a model of self-regulated learning in which to ground the construction of the inventory. This version was tested with 96 graduate students, but technical aspects were not entirely satisfactory. Version 3 represents an attempt to improve the technical properties of the inventory and an effort to clarify and sharpen the model. Version 3, which contained 4 subscales, was tested with 219 undergraduates and 62 graduate students. Reliabilities of this version were higher than those of the other versions, and all subscales and total score correlated with grade point average, with the motivation scale showing the strongest relationship. Results support the model and the potential of the inventory as a means of assessing self-regulated learning. (Contains 2 figures, 12 tables, and 14 references.) (SLD)