This book constitutes the refereed proceedings of the 13th International Conference on Persuasive Technology, PERSUASIVE 2018, held in Waterloo, ON, Canada, in April 2018. The 21 revised full papers and 4 short papers presented were carefully reviewed and selected from 59 submissions. The papers demonstrate how persuasive technologies can help solve societal issues. They explore new frontiers for persuasive technology, such as personalized persuasion, new sensor usage, uses of big data, and new ways of creating engagement through gaming or social connection, focusing on a variety of technologies (e.g., web, wearables, AI, and smart environments). The papers are organized in the following topical sections: social means to persuasion; nudging and just-in-time interventions; design principles and practices; persuasive games; personalization and tailoring; and theoretical reflections.