This book constitutes the proceedings of the 13th International Conference and Workshop on Algorithms and Computation, WALCOM 2019, held in Guwahati, India, in February/ March 2019. The 30 full papers presented were carefully reviewed and selected from 100 submissions. The papers are organized in topical headings on the facility location problem; computational geometry; graph drawing; graph algorithms; approximation algorithms; miscellaneous; data structures; parallel and distributed algorithms; and packing and covering.