Recent decades have seen Georg Simmel's canonical status in American sociology solidify and his impact on research expand. A broad understanding of his influence, however, remains elusive. This review remedies this situation by evaluating Simmel's legacy in American sociology since 1975. We articulate Simmel's sociological orientation by elaborating the concepts of form, interaction, and dualism. Employing a network analysis of references to Simmel since 1975, we examine how Simmelian concepts have been adopted in research. We find Simmel became an anchor for change in urban and conflict studies, where scholars moved from his earlier functionalist reception toward a formalist interpretation. This formalist reception consolidated Simmel's status as a classic in network research and symbolic interactionism during the 1980s. Recent work in economic sociology and the sociology of culture, however, builds on Simmel's growing reception within relational sociology. We conclude with several ways to further articulate Simmel's ideas in the discipline. Expected final online publication date for the Annual Review of Sociology, Volume 47 is July 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.