COMPSAC is a major international forum for researchers, practitioners, managers, and policy makers interested in computer software and applications. The proceedings discusses state of the art, new advances, and future trends in software technologies and practices.The creation of trustworthy and dependable software spans all aspects of software engineering. Building on the trustworthy, secure, and dependable software themes of highly successful recent COMPSAC conferences, the technical theme for the 31st conference is Software Engineering ? Critical Features and Infrastructures COMPSAC 2007 features research and industrial practice papers with a wide range of topics, focusing on the software engineering of critical infrastructure systems such as civil, telecommunications, and medical systems. The papers in COMPSAC cover topics that include requirement analysis, co-analysis and co-design, modeling, design, development, testing, measurement, verification and validation for performance, safety, security, and dependability constraints. Effective construction of these systems is not limited solely to the field of computer science and engineering and is truly a multidisciplinary effort. Multidisciplinary work, research and development software prototypes, industry-university collaborations, all based on new emerging and critical technologies are all part of COMPSAC.Contents: Security in Communication; Modeling Security; Vulnerabilities - Detecting and Assessment; Infrastructure, Networking and Security; Design and Modeling; Putting Models to Run; Event-Based and State-Based Modeling; Ontology for Requirements Elicitation; Analysis and Modeling; Internet and Web-Based Systems; Component-Based Software and Architecture; Embedded systems; Process and Maintenance; Quality of Service and Performance; Quality of Service and Service Composition; Modeling and Validation for Quality of Service; Validation and Assessment; Quantification; Coverage and Prioritization for Testing; Specification and Verification; Analysis and Testing; Quality, Diversity and Services; Process Models; Data, Repositories, Design Methods; Networking and Distribution; Software Engineering Methods and Tools; Software Applications