An instrument was developed to measure students' engagement in various classes of study activities within multiple study contexts. This instrument is to be used in a large, ongoing research project investigating the underpinnings of student study activities and effects on academic achievement. The computer-administered instrument used--the Study Activity Questionnaire (SAQ)--is based on hierarchical models of the cognitive processing and effort management activities involved in academic study. Item types associated with different levels and dimensions of cognitive and effort management hierarchies for routine study and test preparation study were constructed. The SAQ was administered, using a microcomputer, to 235 students enrolled in 14 general biology courses at 7 high schools in the San Francisco Bay area. Results provide insights into the amount of time students engaged in study, allocation of study time, types of activities performed, and focus of cognitive activities. Data concerning students' engagement in the hierarchical study activities are encouraging. The patterns of responses reported for the routine context and the test preparation context were similar. However, the small differences that were found may be important to the extent that students change the character of their study practices in response to specific contextual factors, goals, purposes, or demands. It appears that the design of the SAQ and the microcomputer administration procedure have a great deal of potential for assessment and diagnostics. Fifteen data tables, one figure, and four samples of computer screen text are provided. (TJH)