This book constitutes the refereed proceedings of the 15th International Conference on Persuasive Technology, PERSUASIVE 2020, held in Aalborg, Denmark, in April 2020. The 18 full papers presented in this book were carefully reviewed and selected from 79 submissions. The papers are grouped in the following topical sections: methodological and theoretical perspectives on persuasive design; persuasive in practice, digital insights; persuasive technologies for health and wellbeing; persuasive solutions for a sustainable future; and on security and ethics in persuasive technology.