The development of Life Cycle Applications tools for the Joint Simulation System (JSIMS) is a complex task that requires an understanding of user requirements, systems engineering, object oriented analysis, and training methodologies. This paper describes the process of transforming a large array of user requirements from a multitude of independent sources into a high level system design. This process was characterized by frequent interactions with the users, appropriate application of business process reengineering, and iterative system requirements analysis and functional analysis. Popular object oriented techniques were synthesized into the JSIMS Object-Oriented Process (JOOP) to improve the communication of the requirements set to the simulation developers within the JSIMS Enterprise community. Two very important aspects of the Requirements-to-Software process were a detailed study of the user requirements so that the developers could obtain the proper perspective on Joint and Service Specific training goals, and providing feedback to the partner development programs and ultimately the JSIMS users. This feedback was provided throughout the development process by means of collaborative events such as requirements walk-throughs, high level design peer reviews and web-based electronic or hard copy distribution of analysis documentation such as JOOP context diagrams, use cases, and draft Graphical User Interface screens. Collaborative design tools designed to maximize efficiency were employed to maintain traceability to the user requirements from the beginning of the systems engineering process through software development and test.