Research findings from a study of collective bargaining in New York and Michigan school districts indicate that collective bargaining does have a significant impact on the allocation of resources in ways that affect student learning. These findings support hypotheses based on the theory that collective bargaining will make a difference in resource allocation when the preferences of teachers and management do not coincide. The hypotheses state that, without collective bargaining, management responds to the preferences of marginal teachers (those mobile enough to quit if dissatisfied) because inframarginal teachers (those less mobile) pose less of a threat to district stability. Moreover, inframarginal preferences are more effectively represented when teachers are unionized, and strong unions can significantly alter the outcomes of contract negotiations, affecting teacher control over instructional spending. The research examines relationships among the following factors: union affiliation, district characteristics, kinds of contract provisions, and numbers of contract provisions. Special attention is paid to the impact of enrollment decline on union intersts in collective bargaining. The study found that the stronger the union, the more items covered in the contract, the more resources allocated to instruction, and the more control exercised by teachers in district decision-making. (Author/PGD)