Based primarily on social information processing theory, two purposes guided this investigation: (1) to determine the effects of structural and expenctancy linkages on three indicators of school effectiveness and (2) to assess the stability fo these relationships during a school year. Teachers and students from 89 elementary and secondary schools participated in the study. Data were collected early in the fall semester and late in the spring semester. As a group, the structural and expectancy linkage variables were consistent predictors of the criterion variables, especially later in the school year. The findings support the social information processing model and Mintzberg's conception of professional bureaucracies.