The St. Louis Fed has released a new report on Duty to Serve (DTS), a component of the Housing and Economic Recovery Act of 2008. DTS requires Fannie Mae and Freddie Mac to facilitate a secondary mortgage market in three underserved markets—manufactured housing, affordable housing preservation and rural housing. The goal of the program is to provide more homeownership and rental housing options for households with very low, low and moderate incomes. This Policy Insight provides an overview of the program, which began implementation in January 2018. Visit www.stlouisfed.org/community-development/publications/policy-insights/expanding-affordable-housing-options.