Major Defense Acquisition Programs (MDAP) cost billions of dollars and have 30 to 50 year life spans. Numerous (federal, state, etc.) laws, Environmental Protection Agency (EPA) regulations, and Executive Orders (EO) have driven DoD to develop and implement significant environmental policies within the past ten to fifteen years. Congressional mandate now requires each MDAP to evaluate its environmental life cycle cost (ELCC) to minimize these costs. This research focuses on the current methodologies and models used to predict and calculate the ELCC of a MDAP. This thesis analyzed the difficulties associated with using ELCC methodologies and models and examined several case studies of organizations that have used ELCC methodologies and models.