This book constitutes the thoroughly refereed post-conference proceedings of the 21st International Symposium on Graph Drawing, GD 2013, held in Bordeaux, France, in September 2013. The 42 revised full papers presented together with 12 revised short papers, 3 invited talks and 1 poster description were carefully reviewed and selected from 110 submissions. The papers are organized in topical sections on upward drawings, planarity, beyond planarity, geometric representations, 3D et al., universality, practical graph drawing, subgraphs, crossings, geometric graphs and geographic networks, angular restrictions, grids, curves and routes. The book also contains a short description of the graph drawing contest.