This study reviews and synthesizes evidence from six recent investigations providing data on a total of 112 formal interorganizational arrangements (IOA's) that support educational improvement efforts. The synthesis was undertaken to ascertain how the nature, processes, interactions, and outcomes of such collaborative arrangements can support school improvement. A brief synopsis of each study describes the basic features and assumptions of the IOA's, the study methodology, and the primary findings and interpretations. The cross-study synthesis is then organized around three topics: (1) classification of IOA's according to legal status of the IOA itself and the improvement effort it supports; (2) comparison of various types of IOA's by history, context, structure, operations, and outputs; and (3) a synthesis of key findings, including general cross-study findings and predominant cross-study outcomes in six categories: power and status changes, linkage changes, knowledge transfer, capacity building, practice improvement, and institutionalization. In the final section, implications of the synthesis are provided, respectively, for managers, policymakers, and researchers concerned with educational dissemination and school improvement. References are included. (Author/TE)