  This volume contains the proceedings of the 12th International Workshop on
Quantum Physics and Logic (QPL 2015), which was held July 15-17, 2015 at Oxford
University. The goal of this workshop series is to bring together researchers
working on mathematical foundations of quantum physics, quantum computing,
spatio-temporal causal structures, and related areas such as computational
linguistics. Of particular interest are topics that use logical tools, ordered
algebraic and category-theoretic structures, formal languages, semantical
methods and other computer science methods for the study of physical behaviour
in general.
