Successes to date with the use of integrated software framework tools have led NASA engineers and other researchers to expand the breadth, depth, and sophistication of the problems that they are attempting to solve. Both the utilization of "high-fidelity" physics based models ("depth") and the total number of different engineering disciplines included in system models ("breadth") have steadily increased. As model size and complexity grows, the number of engineers involved in the development and maintenance of these models is also increasing. Increases in system model size and complexity and the corresponding need for collaborative model development are beginning to stretch the limits of existing software frameworks. Large models are more difficult to build and maintain, while the inclusion of more people in the development process leads to model management and coordination issues. Enhanced and improved framework tools are required if NASA and industry are to continue to expand their modeling, simulation, and design capabilities. In this project, Phoenix Integration will develop an innovative software environment that will allow individual engineers and collaborative engineering teams to better build and manage large, complex, system models. Key elements in the solution include a new infrastructure for hierarchical model building (models within models), enhanced data linking and model verification tools, and an integrated version-controlled model and data library. These tools will combine to provide NASA engineers with a powerful and flexible environment for creating, maintaining, and collaborating on the creation, execution, and maintenance of large and complex system models.