Housing costs constitute the single biggest expenditure in most family budgets, and many low-income families have difficulty finding housing they can reasonably afford. Although most family-strengthening and community change initiatives recognize the urgency of the housing problems facing low-income families, they often have difficulty figuring out how to constructively address them. Federal housing programs are numerous and confusing, implementation is balkanized, funding falls woefully short of needs, and policy debates often focus on narrow technical issues. This primer demystifies federal rental assistance programs and provides the most current information available on how many (and who) they serve and how their scale is changing. It also summarizes key challenges facing housing policy today and in the coming yearschallenges that may create opportunities for federal, state, and local engagement and innovation.