Mentored undergraduate research has been identified as a high-impact practice that enhances teaching and learning in higher education. It is reported to influence students' academic, affective, and behavioral outcomes. However, there is only an emerging literature related to student outcomes associated with identity development, specifically students' personal and professional identities. This integrative literature review examines the intersections and interrelationship across mentoring, undergraduate research, and student identity development. Its results uncover the complexity of the constructs, and their dynamic interrelationship, especially when viewed through the lenses of the sociocultural perspective grounded in the notion of mediated action. Two assumptions undergird this perspective: first, that all investigation takes place at the intersection of these constructs with mediated action, not individuals in isolation, as a unit of analysis; and, second, that any study of identity must focus on an understanding of identity as multiple, dynamic, and situated in personal and cultural contexts (institutional, disciplinary, and external community culture and values). Thus, the sociocultural perspective and its underlying assumptions shape the proposed research agenda. This research agenda has the potential to advance current knowledge related to mentored undergraduate research and the confluence of elements that contribute to student personal and cultural identities (academic, disciplinary, and professional). Findings from this work will inform our understanding of learning and knowledge construction in sociocultural context, and the trajectory of identity development of students engaged in high-impact learning experiences.