Bidirectional transformations (BX) are means of maintaining consistency between multiple information sources: when one source is edited, the others may need updating to restore consistency. BX have applications in databases, user interface design, model-driven development, and many other domains.This volume represents the lecture notes from the Summer School on Bidirectional Transformations, held in Oxford, UK, in July 2016. The school was one of the final activities on the project "A Theory of Least Change for Bidirectional Transformations", running at the University of Oxford and the University of Edinburgh from 2013 to 2017 and funded by the UK Engineering and Physical Sciences Research Council. The five chapters included in this volume are a record of most of the material presented at the summer school. After a comprehensive introduction to bidirectional transformations, they deal with triple graph grammars, modular edit lenses, putback-based bidirectional programming, and engineering of bidirectional transformations.