New Zealand has among the highest rates of roll your own (RYO) tobacco use internationally; RYO causes particular harm to Māori, young adults and people experiencing lower prosperity. Increasing the costs of RYO tobacco has led some smokers to forgo essential items and stimulated calls for new approaches. Using a parallel process for Māori and non-Māori, we will develop and test RYO-specific high-affect warnings, and assess how these affect users’ beliefs and quitting behaviours when combined with efficacy messages that enhance quitters’ confidence. Whānau and in-depth interviews will identify optimal warnings and efficacy messages; a survey will test the communication effectiveness of these stimuli, and a choice experiment will compare individual stimuli and interactions between these. Conducted in partnership with Hāpai te Hauora, our research will provide the first evidence of how tailored RYO warnings and efficacy messages influence cessation-related beliefs and behaviours among groups most affected by RYO use.