The Self-Regulated Learning Inventory was developed to help researchers and teachers understand the concept of self-regulated learning and to provide a tool for identifying behaviors students need for academic success. Version One of the instrument contained 71 items representing the factors of metacognition, learning strategies, motivation, contextual sensitivity, and environmental control/utilization. Following a pilot study with responses of 104 undergraduates, a second version was constructed based on a formalized provisional model of self-regulated learning. A number of unpublished studies were conducted to evaluate Version Two, and these led to the construction of a third version based on a four-factor model of executive processing, cognitive processing, motivation, and environment control/utilization. Version 3 contained 80 items, divided evenly among the 4 subscales. Testing with 219 undergraduates and 62 graduate students supported the reliability of the version. Separate factor analyses for graduate and undergraduate students supported a four-factor solution in either case. Results from this study suggested a strong relationship between self-regulated learning and grade point average. (Contains 7 tables, 1 figure, and 18 references.) (SLD)