As states move beyond simply managing their homelessness crises to looking for ways to reduce and ultimately end homelessness, broad-scale efforts to prevent homelessness are lacking. Experiences of homelessness are often harmful, traumatic, and costly, making a compelling case for why homelessness prevention should be prioritized. In recent years, countries such as Australia, Finland, and Wales have shifted their focus to prevention, but there remains a conceptual and systematic gap in our collective knowledge about what precisely homelessness prevention is, what policies, programs, and interventions are captured in a homelessness prevention strategy, and how to build a framework for orienting our response to homelessness towards prevention. This article begins to fill that gap by providing a definition and typology of homelessness prevention (THP). Our definition offers a schema to clarify the nature of homelessness prevention and to develop a collective response between various policies and practices that can and should be framed as homelessness prevention. Building off of the public health model of prevention and pre-existing homelessness prevention classification systems, our THP complements the definition by specifying the pragmatic nature of prevention initiatives and the range of sectors, stakeholders, and levels of government required to respond to the causes of homelessness. Our typology is made up of five interrelated elements: structural, systems, early intervention, evictions prevention, and housing stabilization. Each of these elements contains actionable strategies that cut across primary, secondary, and tertiary prevention to ensure that people at various levels of risk have access to the tools and resources necessary to find and maintain safe, appropriate, and suitable housing. Together the definition and THP are useful tools to envision a new way forward in how we respond to homelessness.