The progress made by 24 League of Professional Schools in increasing the variety, collection, and use of data during 1990-91 is examined in this paper. Three goals of the league are to involve schools in action research for school improvement, increase teacher participation through shared governance, and develop school improvement initiatives. Methodology involved analysis of the 24 schools' action plans, 2 planning surveys, and conference discussions. Findings indicate that participating school teams need information about assessment devices--particularly availability and procedures--and formulation of specific assessment goals. Confrontation with data initiates action for change, often producing beneficial outcomes. Four tables and two figures are included. (18 references) (LMI)