Lesbian, gay, and bisexual (LGB) adults in the United States have a higher prevalence of smoking than their heterosexual counterparts. In 2013, the Los Angeles County Department of Public Health launched a social marketing and outreach campaign called Break Up to reduce the prevalence of smoking in LGB communities. Break Up was evaluated using cross-sectional, street-intercept surveys before and near the end of campaign. Surveys measured demographics, campaign awareness, and self-reported smoking-related outcomes. Bivariate statistics and logistic regression models were used to identify whether campaign awareness was associated with smoking-related outcomes. Calls by LGB persons to a smokers' helpline were also measured. Among those interviewed at endline, 32.7% reported Break Up awareness. Awareness was associated with thinking of quitting smoking and ever taking steps to quit but not with smoking cessation (defined as not smoking in the past 30 days among those who had smoked in the past 6 months). There was a 0.7% increase in the percentage of weekly calls by LGB persons to the helpline in the year after the campaign. Break Up reached about a third of its intended audience. The campaign was associated with smoking cessation precursors and may have led to an increase in helpline utilization, but there is no evidence it affected quit attempts. This study adds to the limited literature on tobacco programs for LGB persons and, as far as we know, is one of the first to evaluate tobacco-free social marketing in this important yet understudied population.