Enterprise architecture is a collection of artifacts describing various aspects of an organization from an integrated business and IT perspective. Practicing enterprise architecture in organizations implies using these artifacts to facilitate information systems planning and improve business and IT alignment. Despite its long history, the enterprise architecture discipline still remains largely atheoretical and lacks a solid theoretical basis. Based on our previous empirical studies of the practical usage of enterprise architecture artifacts in multiple organizations and broad literature analysis, this conceptual article identifies and discusses in detail 10 theories that can be considered key for understanding how an enterprise architecture practice works: actor-network theory, boundary objects theory, cognitive fit theory, communities of practice theory, decision-making theories, information processing theory, knowledge management theory, management fashion theory, media richness theory, and uncertainty principle. Taken together, these theories offer a comprehensive theoretical view of an enterprise architecture practice explaining the role of enterprise architecture artifacts, their usability, and participation of stakeholders and, therefore, may constitute a theoretical basis of the entire enterprise architecture discipline. Although this article does not elaborate on any of these theories, it brings these theories to light, establishes their critical importance for comprehending an enterprise architecture practice, and positions them as central to the enterprise architecture discourse. Each of these theories can be leveraged by enterprise architecture scholars in their future studies for analyzing enterprise architecture practices through respective theoretical lenses. This article intends to provide fresh theoretical insights on enterprise architecture, spark new waves of theoretical enterprise architecture research, and contribute to the development of a sound theoretical foundation for the enterprise architecture discipline.