Discretion Within Constraint: Homophily and Structure in a Formal Organization

Homophily in social relations results from both individual preferences and selective opportunities for interaction, but how these two mechanisms interact in large, contemporary organizations is not well understood. We argue that organizational structures and geography delimit opportunities for interaction such that actors have a greater level of discretion to choose their interaction partners within business units, job functions, offices, and quasi-formal structures. This leads us to expect to find a higher proportion of homophilous interactions within these organizational structures than across their boundaries. We test our theory in an analysis of the rate of dyadic communication in an email data set comprising thousands of employees in a large information technology firm. These findings have implications for research on homophily, gender relations in organizations, and formal and informal organizational structure.