This book constitutes the proceedings of the First International Workshop on Dynamic Logic, DALI 2017, held in Brasilia, Brazil, in September 2017. Both its theoretical relevance and practical potential make Dynamic Logic a topic of interest in a number of scientific venues, from wide-scope software engineering conferences to modal logic specific events. The workshop is promoted by an R&D project on dynamic logics for cyber-physical systems. The 12 full papers presented in this volume were carefully reviewed and selected from 25 submissions. The workshop is based on the project DaLi - Dynamic logics for cyber-physical systems: towards contract based design.