For reasons such as this, researchers have spent a great deal of time creating and empirically studying various techniques for improving the cost-effectiveness of regression testing. Despite the progress this research has achieved to date, three important aspects of the regression testing problem have not been considered: (1) factors involving the context in which testing occurs; (2) assessment of regression techniques across entire system lifetimes; (3) proper economic models that capture important cost factors and quantify benefits of regression testing techniques ands strategies. This project addresses these issues by performing the following activities: (1) creating cost-effective regression testing techniques that address the testing process and domain contexts, (2) creating regression testing strategies that address system lifetimes, (3) creating economic models that enable the adequate assessment of techniques and strategies, and (4) evaluating and refining these techniques and strategies through rigorous empirical approaches. This work will lay a foundation for evaluating the cost-effectiveness of various regression testing techniques and strategies in practical ways. Further, the discoveries made by this work will promote software dependability, with potential benefits to all organizations and persons who depend on that software.