PurposeThis study aims to apply and test the effectiveness of message sidedness and conclusiveness in Google Ads advertising.Design/methodology/approachFour field experiments on Google Ad campaigns were conducted on the topics of energy and environment, the water–energy–food nexus, and a Higher-Ed program (at the national and local levels).FindingsTwo-sided search engine advertisements are more effective than one-sided advertisements in national campaigns but less effective in local campaigns. In national campaigns, conclusive search engine advertisements are more effective in increasing impressions and clicks, but inconclusive advertisements are more effective in increasing the click-through rate (CTR); in local campaigns, inconclusive advertisements are more effective when being one-sided, while conclusive advertisements are more effective when being two-sided. Overall, the two-sided and inconclusive advertisement generates the best results in a national campaign, but the one-sided and inconclusive advertisement generates the best results in a local campaign.Originality/valueAs the first to test sidedness and conclusiveness with Google Ads advertising, the paper provides theoretical and practical suggestions to search engine marketers by identifying the effective copywriting strategies, moderating factors and more measurements of effectiveness.