Nonsuicidal self-injury (NSSI) is a widespread and dangerous behavior. Despite increasing understanding of the risk factors for NSSI, this behavior remains highly prevalent, highlighting the need for an extension of current research and more precise treatment targets. Specifically, research examining self-perception in NSSI provides a fruitful foundation for future work. Mounting studies indicate that self-concept disturbances are implicated in NSSI. Yet it remains unclear how different components of self-concept—such as self-criticism and identity confusion—are associated for people with NSSI. Furthermore, research in this domain uses distinct definitions and measures of self-concept disturbance, rendering it difficult to integrate findings across studies. This conceptual review provides the first summary to date synthesizing research on self-concept (content and structure) in NSSI, highlights research questions to address, and outlines suggestions for future work. Recommendations for NSSI research examining self-concept include: (a) increasing the consistency of terms used; (b) examining relationships between self-concept content and structure; (c) exploring the extent to which measures of self-concept and identity tap into the same phenomena; (d) assessing self-concept across different levels of analysis; and (e) identifying treatment targets for distinct self-related disturbances (e.g., heightened self-criticism versus an inconsistent sense of self). Potential intervention targets are discussed.