This article offers a novel perspective on self-construal theory. Self-construal concerns how individuals understand who they are in relation to the broad set of cultural influences in which they live. We look at the nature and antecedents of self-construal, and characterize it as a self-process, rather than self-knowledge. Integrating work from the literature on social and evolutionary psychology, and philosophy, we suggest that the differences between independent and interdependent self-construal are best understood from a self-agency perspective. This concerns how people assess whether they are the causes of an action and, if so, whether their causal role depends on other people. We introduce and discuss the roles of 3 different modalities of agency involved in self-agency assessment: implicit (sensorimotor), intermediate (self-related affordances), and explicit (reflective) self-agency. We offer a conceptual model on how self-agency relates to power, evolutionary motivations and to social and cultural affordances, in the formation of, and interaction with, different types of dominant independent and interdependent self-construals.