This paper describes the impact of the Ada programming lan guage on the development and use of simulation models. Based upon the development in Ada of a discrete-event simulation package (A*SIM), Ada is shown to provide numerous language features and methodologies that are ideally suited for modeling and simulation. Productivity and performance metrics collected during development and extensive use of A*SIM are also pre sented to provide quantitative comparisons of Ada-based model ing and simulation with previous approaches.