This book constitutes the refereed proceedings of the Second International Symposium on Engineering Secure Software and Systems, ESSoS 2010, held in Pisa, Italy, in February 2010. The 9 revised full papers presented together with 8 ideas papers were carefully reviewed and selected from 58 submissions. The papers are organized in topical sections on attack analysis and prevention, policy verification and enforcement, and secure system and software development. It is our pleasure to welcome you to the proceedings of the Second International Symposium on Engineering Secure Software and Systems. This unique event aimed at bringing together researchersfrom softwareen- neering and security engineering, which might help to unite and further develop the two communities in this and future editions. The parallel technical spons- ships from the ACM SIGSAC (the ACM interest group in security) and ACM SIGSOF (the ACM interest group in software engineering) is a clear sign of the importance of this inter-disciplinary research area and its potential. The di?culty of building secure software systems is no longer focused on mastering security technology such as cryptography or access control models. Other important factors include the complexity of modern networked software systems, the unpredictability of practical development life cycles, the intertw- ing of and trade-o? between functionality, security and other qualities, the d- culty of dealing with human factors, and so forth. Over the last years, an entire research domain has been building up around these problems. The conference program included two major keynotes from Any Gordon (Microsoft Research Cambridge) on the practical veri?cation of security pro- cols implementation and Angela Sasse (University College London) on security usability and an interesting blend of research, industry and idea papers.