Purpose The purpose of this paper is to evaluate the effectiveness of a national alcohol-prevention social marketing campaign in Thailand, investigating specifically the competing forces of the campaign vis-à-vis alcohol advertising. Design/methodology/approach Based on repeated cross-sectional, nationally representative data from the 2011-2014 Annual Survey of Buddhist Lent Campaign Evaluation (N = 10,133), a generalized ordered logit (partial proportional odds) model is used. The outcome of interest is self-reported alcohol consumption during the campaign period, compared to before. The main explanatory variables include exposure to the campaign and exposure to alcohol advertising. Findings Results show that exposure to the campaign and exposure to alcohol advertising positively and negatively influence alcohol consumption, respectively. Compared to those with one type of exposure and those without any exposure to alcohol-related messages, drinkers with exposure to both the campaign and alcohol advertising are estimated to have the highest probability of drinking reduction during the campaign period. Originality/value The paper highlights the importance of accounting for a countervailing force (in this case, alcohol advertising) in campaign evaluation studies. It also suggests that alcohol-control social marketing be continued and that the government should disseminate alcohol-prevention messages in a balanced manner, ensuring that both costs and benefits of alcohol consumption are well-understood by the intended audience.