Social media are key arenas for public opinion formation, but are susceptible to coordinated social media manipulation (CSMM), that is, the orchestrated activity of multiple accounts to increase content visibility and deceive audiences. Despite advances in detecting and characterizing CSMM, the attribution problem—identifying the principals behind CSMM campaigns—has received little scholarly attention. In this article, we address this gap by synthesizing existing research and developing a theoretical model for understanding CSMM. We propose a consolidated definition of CSMM, identify its key observable and hidden characteristics, and present a rational choice model for inferring principals’ strategic decisions from campaign features. In addition, we present a typology of CSMM campaigns, linking variations in scale, elaborateness, and disguise to principals’ resources, stakes, and influence strategies. Our contribution provides researchers with conceptual and heuristic tools for attribution and invites interdisciplinary and comparative research on CSMM campaigns.