The central argument of network research is that actors are embedded in networks of interconnected social relationships that offer opportunities for and constraints on behavior. We review research on the antecedents and consequences of networks at the interpersonal, interunit, and interorganizational levels of analysis, evaluate recent theoretical and empirical trends, and give directions for future research, highlighting the importance of investigating cross-level network phenomena.A quarter century of social network research in management journals has resulted in the accumulation of many findings in recent years (see, for example, Borgatti and Foster [2003] for a recent review). Network studies have appeared regularly in management journals, contributing to the investigation of a wide range of organizational topics across different levels of analysis (for a discussion of the concepts, techniques and measures in network analysis, see, for example, Wasserman and Faust [1994]). The purpose of this article is to evaluate organizational network research. Where have we been? What do we know? Where are we going? To that end, we take stock of the results of organizational network research at the interpersonal, interunit, and interorganizational levels of analysis, focusing on the antecedents and consequences of networks at each level. We hope to generate future research directions by assessing where network scholarship currently is.Network research embraces a distinctive perspective that focuses on relations among actors, whether they are individuals, work units, or organizations. According to the network perspective, actors are embedded within networks of interconnected relationships that provide opportunities for and constraints on behavior. This perspective differs from traditional perspectives in organizational studies that examine individual actors in isolation. The difference is the focus on relations rather than attributes, on structured patterns of interaction rather than isolated individual actors. It is the intersection of relationships that defines an individual's centrality in a group, a group's role in an organization (White, Boorman, & Breiger, 1976), or an organization's niche in a market (McPherson, 1983).We define a network as a set of nodes and the set of ties representing some relationship, or lack of relationship, between the nodes. We refer to the nodes as actors (individuals, work units, or organizations). The particular content of the relationships represented by the ties is limited only by a researcher's imagination. Typically studied are strategic alliances and collaborations, flows of information (communication), affect (friendship), goods and services (work flow), and influence (advice), and overlapping group memberships such as boards of directors. We consider ties that are maintained over time, thus establishing a relatively stable pattern of network interrelationships.Using this network perspective, organizational researchers have been able to explain variance in such traditional organiza...
