Little is known about whether media campaigns are effective strategies to promote smoking cessation among socioeconomically disadvantaged populations or whether media campaigns may unintentionally maintain or widen disparities in smoking cessation by socioeconomic status (SES). This paper presents a systematic review of the literature on the effectiveness of media campaigns to promote smoking cessation among low SES populations in the USA and countries with comparable political systems and demographic profiles such as Canada, Australia and Western European nations. We reviewed 29 articles, summarizing results from 18 studies, which made explicit statistical comparisons of media campaign effectiveness by SES, and 21 articles, summarizing results from 13 studies, which assessed the effectiveness of media campaigns targeted specifically to low SES populations. We find that there is considerable evidence that media campaigns to promote smoking cessation are often less effective, sometimes equally effective, and rarely more effective among socioeconomically disadvantaged populations relative to more advantaged populations. Disparities in the effectiveness of media campaigns between SES groups may occur at any of three stages: differences in meaningful exposure, differences in motivational response, or differences in opportunity to sustain long-term cessation. There remains a need to conduct research that examines the effectiveness of media campaigns by SES; these studies should employ research designs that are sensitive to various ways that SES differences in smoking cessation media effects might occur.