A formal approach to security in the software life cycle is essential to protect corporate resources. However, little thought has been given to this aspect of software development. Traditionally, software security has been treated as an afterthought leading to a cycle of ?penetrate and patch.? Due to its criticality, security should be integrated as a formal approach in the software life cycle. Both a software security checklist and assessment tools should be incorporated into this life cycle process. The current research at JPL addresses both of these areas through the development of a Software Security Assessment Instrument (SSAI). This paper focuses on the development of a Software Security Checklist (SSC) for the life cycle. It includes the critical areas of requirements gathering and specification, design and code issues, and maintenance and decommissioning of software and systems.