This book constitutes the proceedings of the 13th International Conference on Parallel Computing Technologies, PaCT 2015, held in Petrozavodsk, Russia, during August / September 2015. The 37 full papers and 14 short papers presented were carefully reviewed and selected from 87 submissions. The papers are organized in topical sections on parallel models, algorithms and programming methods; unconventional computing; cellular automata; distributed computing; special processors programming techniques; applications.