U.S. Frontiers of Engineering (USFOE) symposia bring together 100 outstanding engineers (ages 30 to 45) to exchange information about leading-edge technologies in a range of engineering fields. The 2007 symposium covered engineering trustworthy computer systems, control of protein conformations, biotechnology for fuels and chemicals, modulating and simulating human behavior, and safe water technologies. Papers in this volume describe leading-edge research on disparate tools in software security, decoding the "mechanome," corn-based materials, modeling human cultural behavior, water treatment by UV irradiation, and many other topics. A speech by dinner speaker Dr. Henrique (Rico) Malvar, managing director of Microsoft Research, is also included. Appendixes provide information about contributors, the symposium program, summaries of break-out sessions, and a list of participants. This is the thirteenth volume in the USFOE series.