PURPOSE: Community members and non-academic partners ("affected groups") were asked to identify factors that can influence public support, impede adoption, and mitigate challenges related to adopting local smoke-free multi-unit housing policies. APPROACH: A series of key informant interviews were conducted with affected groups from a large U.S. metropolitan area. SETTING: 20 cities in Los Angeles County without a smoke-free multi-unit housing ordinance. PARTICIPANTS: Interviewees were recruited from affected groups with knowledge about their community's civic and political landscape (n = 63). METHOD: Data were collected and analyzed using thematic analysis to identify, code and compare themes. RESULTS: Most interviewees indicated civic groups, those who do not smoke, and/or groups who are educated about the negative health effects of secondhand smoke exposure would be more likely to support smoke-free multi-unit housing policies. Interviewees reported several challenges to policy adoption, including competing city priorities, public disengagement, and the cost and social burden of enforcing these ordinances. To overcome them, interviewees recommended working synergistically with local governments to build diverse coalitions, educate the public, and develop clear enforcement plans. CONCLUSION: Insights and recommendations from affected groups in 20 U.S. cities suggest that communicating with the public and priming impacted communities to support smoke-free multi-unit housing policies are promising interventions for protecting at-risk families from secondhand smoke exposure in their homes.