This book constitutes the refereed proceedings of the 13th Conference on Computability in Europe, CiE 2017, held in Turku, Finland, in June 2017. The 24 revised full papers and 12 invited papers were carefully reviewed and selected from 69 submissions. The conference CiE 2016 has six special sessions, namly: algorithmics for biology; combinatorics and algorithmics on words; computability in analysis, algebra, and geometry; cryptography and information theory; formal languages and automata theory; and history and philosophy of computing.