The Ada programming language and the associated software engineering disciplines have been described as one of the most significant developments in software technology in many years. Although many claims have been made about its advantages and impacts, there have been very few empirical studies that clarify the impact of Ada. The Software Engineering Laboratory (SEL) is an organization sponsored by the National Aeronautics and Space Administration (NASA) consisting of three principal members: NASA/Goddard Space Flight Center, the University of Maryland, and Computer Sciences Corporation. The SEL was founded in 1976 to carry out studies and measurements related to evolving software technologies. The studies are aimed at understanding both the software development process and the impacts that evolving software practices may have on the software process and product. Since 1976, the SEL has conducted over 65 experiments by applying selected techniques to specific development efforts and measuring the resulting process and product. In early 1985, the SEL initiated an effort to study the characteristics, applications, and impacts of Ada. Beginning with a relatively small practice problem (6000 source lines of Ada), the SEL has collected detailed development data from a total of eight Ada projects (some of which are still ongoing). The projects range in size from 6000 lines to approximately 160,000 lines of code.