This document contains reports examining research designs for Educational Resources Information Center (ERIC) usage studies at three levels: (1) system operations; (2) subscribers to the services provided; and (3) the ultimate "end-users" of the service. The first level report, which addresses ERIC as an information network, proposes two changes which would provide greater coordination and cohesion for the system--the development of a more hierarchical network articulation of the ERIC system, and a systematic reporting system a part of a more formal management information system. This report describes a framework for comprehending, examining, and managing the ERIC system; describes ueful data categories and appropriate levels of data collection; suggests a method of developing a model data collecting system; and examines these suggestions with present possibilities. The second level report recommends non-experimental approaches to ERIC use assessments and examines methodological and research design considerations for ERIC usage studies. The third level report focuses on ERIC impact studies, i.e., how ERIC products and services have affected the end-user. General methodological recommendations are made for particular studies, and all available ERIC impact studies are analyzed in terms of these recommendations, and in terms of the specific impact measures employed. Research plans for future impact studies are included. (CWM)