To examine attitudes toward smoke-free policies and perceptions of e-cigarette use among homeless adults.A cross-sectional qualitative study was conducted.Study setting comprised seven transitional homeless shelters with indoor smoke-free policies in San Diego County; facilities differed in outdoor restrictions on smoking.Sixty-six current or former smokers were the study participants.Participants completed a questionnaire on smoking behaviors, perceived antitobacco norms, and attitudes toward smoke-free policies, and attended a focus group interview that explored these topics. We used a directed content analysis approach to analyze the focus group transcripts.Clients in facilities with outdoor restrictions on smoking had stronger perceived antitobacco norms than those in facilities without such restrictions. We identified the following major themes: attitudes toward smoke-free policies, the use of e-cigarettes, the addictive potential of cigarettes, vulnerability to tobacco industry marketing, and interest in smoking cessation. The consensus was that smoke-free policies were important because they limited secondhand smoke exposure to nonsmokers and children. All were curious about e-cigarettes, particularly if they could be smoked in areas where smoking was prohibited and/or used as a cessation aid.In this study of homeless adults, there was strong support for indoor and outdoor smoke-free policies. However, misperceptions that e-cigarettes could be used indoors could threaten antitobacco norms, highlighting opportunities to educate about the potential risks of e-cigarette use among homeless individuals.