This chapter examines historical materialism and its approach to understanding what constitutes security. It begins with an overview of of the social scientific, philosophical, and political dimensions of historical materialism and what it involves, including its diversity, value, and potential but avoidable pitfalls. It then describes key concepts of historical materialism and uses them to show how capitalism generally and in its recent neoliberal form aim to generate insecurity for labour and security for capital. It also discusses the relationships between historical materialism and approaches to security in a wider context (realism, liberalism, social constructivism, and gender) and to various perspectives on security (securitization and the sectoral approach, peace studies, Critical Security Studies, and human security). The chapter concludes with an overall assessment of the contribution of historical materialism to the scholarship and politics of security and insecurity.