AJS Volume 113 Number 1 (July 2007): 205–42 205  2007 by The University of Chicago. All rights reserved. 0002-9602/2007/11301-0006$10.00 Building Solidarity through Generalized Exchange: A Theory of Reciprocity 1 Linda D. Molm University of Arizona Jessica L. Collett University of Notre Dame David R. Schaefer Arizona State University Despite the prevalence of generalized exchange in social life, few studies have investigated the classic anthropological prediction that generalized (indirect) exchange produces greater social solidarity than restricted (direct) exchange. Building on recent work comparing negotiated and reciprocal forms of direct exchange, the authors de- velop a theory of reciprocity in exchange. The theory argues that two structural characteristics of reciprocity distinguish among all three forms of exchange and affect the emergence of social solidarity through three causal mechanisms. Experimental results provide strong support for the causal logic of the theory and for the predicted ordering of subjective dimensions of solidarity across the three forms of exchange, with generalized indirect exchange 1 reciprocal direct exchange 1 negotiated direct exchange. From the kinship structures of primitive peoples, to the barn raisings of 19th-century America, to the vast sharing of software and information on the modern Internet, systems of generalized exchange have always been a ubiquitous part of social life. Scholars have proposed that gen- eralized exchange may help buffer resource fluctuations (Cashdan 1985), 1 This research was supported by a grant from the National Science Foundation (no. SES-0217287) to the first author. We gratefully acknowledge NSF’s support; the re- search assistance of Lorien Lake, Omar Lizardo, Emily Williams, and Seth Wright; and the helpful comments of AJS reviewers. The contributions of the second and third authors are equal. Direct correspondence to Linda D. Molm, Department of Sociology, University of Arizona, Tucson, Arizona 85721. E-mail: molml@u.arizona.edu