This book constitutes the thoroughly refereed post-conference proceedings of the 20th International Symposium on Graph Drawing, GD 2012, held in Redmond, WA, USA, in September 2012. The 42 revised full papers presented together with 4 revised short papers and 8 poster descriptions were carefully reviewed and selected from 92 submissions. They cover a wide range of topics in two main tracks: combinatorial and algorithmic aspects, and visualization systems and interfaces. In addition, reports of the 19th Annual Graph Drawing Contest, which was held during the conference, and of a workshop on theory and practice of graph drawing to celebrate Professor Peter Eades' 60th birthday are included in the volume.

The 16th International Symposium on Graph Drawing (GD 2008) was held in Hersonissos, near Heraklion, Crete, Greece, September 21-24, 2008, and was attended by 91 participants from 19 countries. In response to the call for papers the Program Committee received 83 s- missions, eachdescribing originalresearchand/or a systemdemonstration.Each submissionwasreviewedbyatleastthreeProgramCommitteemembersandthe reviewer's comments were returned to the authors. Following extensive disc- sions, the committee accepted 31 long papers and 8 short papers. In addition, 10 posters were accepted and displayed at the conference site. Each poster was granted a two-page description in the conference proceedings. Two invited speakers, Jesper Tegn er from Karolinska Institute (Monday) and Roberto Tamassia from Brown University (Tuesday), gave fascinating talks during the conference. Professor Tegn er focused on the challenges and oppor- nities posed by the discovery, analysis, and interpretation of biological networks to information visualization, while Prof. Tamassia showed how graph drawing techniques can be used as an e?ective tool in computer security and pointed to future research directions in this area. Following what is now a tradition, the 15th Annual Graph Drawing Contest was held during the conference, also including a Graph Drawing Challenge to the conference attendees. A report is included in the conference proceedings."