The aging and shrinking of skilled workforces already has been, and will continue to be, a major challenge for organizations, particularly in highly developed economies. In light of the massive wave of retirements of members of the baby boomer generation, the retention of valuable organizational knowledge from older and retiring workers has been identified as an urgent need. Surprisingly, research on this specific area of knowledge transfers in organizations is scarce, the nature and antecedents of the knowledge retention process are not yet well understood, and an integrated conceptual framework is missing. As a first step to address these limitations, we conducted a systematic literature review. We summarized the existing literature on knowledge retention according to the 4 main antecedents of knowledge transfers: knowledge, individual, relationship, and contextual characteristics. Furthermore, we examined the nature of the knowledge retention process and identified theories that can explain the proposed relationships. We developed a conceptual framework of knowledge retention that specifies the most relevant antecedents, clarifies how this process unfolds, and summarizes the theoretical foundations. Finally, we utilized the conceptual framework to propose research questions, to identify avenues for future research, and to derive implications for practitioners.