Despite the drastic cutbacks in defense spending, military expenditure on software and software intensive programs continues to grow at a fairly rapid rate. Rather than develop new programs, many of the project initiatives on the drawing boards in military Program Offices involve modifications to existing systems and using existing resources to the fullest extent. This is partly due to the latest DoD instructions, Number 5000.2, “Defense Acquisition Policies and Procedures,” (February 23, 1991), which mandates the use of existing systems over development of new programs. Another source of responsibility for this policy is the belief that modifying or adapting existing software will be less expensive than developing a brand new program. Accurately estimating software programs becomes a critical need to make this determination.