This handbook provides guidance to organizational and social science scholars interested in pursuing multilevel research. Organizational relationships are complex. Employees do their work as individuals, but also as members of larger teams. They exist within various social networks, both within and spanning organizations. Multilevel theory is at the core of the organizational sciences, and unpacking multilevel relationships is fundamental to the challenges faced within these disciplines. Yet, guidance about how to pursue multilevel research has often been siloed within subdomains. In this book, prominent experts on multilevel research guide scholars in the social and behavioral sciences who wish to consider the implications that multilevel research may have for their work. Although the majority of contributors to this handbook have backgrounds in the organizational sciences, the chapters are accessible to researchers from a wide array disciplines including, but not limited to, communication, education, sociology, psychology, and management.