This report compares two approaches to measuring task interdependence, a theoretically fruitful concept for analyzing an organization's technical system. Task interdependence exists among operating personnel in the degree that task performance of one operative constrains, augments, or otherwise poses contingencies for the performance of another. Of particular interest are contingencies that arise by virtue of workers' relative location in the workflow. The movement of pupils from one teacher to another for instruction, or "pupilflow," is the educational analogue of workflow. A self-report questionnaire developed in 1976 at Stanford University was compared with an objective approach developed at the University of Oregon, in which teachers were asked to record for 10 consecutive days the particular pupils whom they taught at any time during the day in each of five subject areas. After logs were obtained from the teachers, the data was assembled to reveal pupilflows and the teachers connected by them. Twenty-nine schools participated in the study; of these, approximately half had begun implementing Individually Guided Education Multiunit School programs two years earlier, while the other half served as controls. Results showed disappointingly low correspondence between the two measurement approaches. The paper offers a conceptualization of task interdependence for interpreting measures and for relating them to four common patterns of instructional organization--team teaching, cross-grouping, departmentalization, and the self-contained classroom. Tables of data appear throughout the report. (AA)