Public television in the U.S. is examined as a public sphere institution through the case of the Wisconsin Collaborative Project (WCP), a programming cooperative contributing to the national PBS schedule. The prevailing model of the organizational field of public television is revised to analyze the expansion of horizontal exchange, diversity, and decentralization represented by the WCP, and thus the capacity of public television to fulfill its public sphere mission.The contentious debate on the structure of the public sphere in the capitalist democracies has begun to move into the field of mass communication, yet there are few empirical investigations of public sphere media institutions and their functions. By exploring the organizational constraints on the public television network and mid-sized stations through a case study of the Wisconsin Collaborative Project, this paper will show how decentralization in organizational structure has contributed to greater diversity in the public television system.The Wisconsin Collaborative Project (WCP) of Wisconsin Public Television was formally founded in 1992 to produce magazine-style news and public affairs programs for national distribution. The WCP weaves together contributions from small and medium-sized public television stations, and offers these programs to all stations via the PBS satellite system. Drawing from interviews and participant observation at Wisconsin Public Television from 1991 to the present, I show how the WCP emerged as a horizontal structure of exchange within the public television system, and argue that this structure augments democratic participation within that system.'This combination of organizational decentralization and diversification of both program content and contributors opens the public television system to greater participation, and in doing so fulfills several important preconditions for an expansion of public television into a more authentic public sphere institution. A central premise of this paper is that despite its limits, the U.S. public television system "weak public service provider embedded in a dominant commercial system" still provides a significant institutional network from which efforts at forging a broader public discourse might emerge. I do not claim that public television per se constitutes a public sphere, much less the Wisconsin Collaborative Project in isolation. Rather, I attempt to show how public space can and Lewis A. Friedland (Ph.D., Brandeis University, 1985) is Assistant Professor in the School of Journalism and Mass Communication, University of Wisconsin-Madison. His research interests include the empirical structure of the contemporary public sphere, electronic communication networks, and social networks and community structure. This manuscript was accepted for publication in December 1994.