Program dependence graphs have been proposed for use in optimizing, vectorizing, and parallelizing compilers, and for program integration. This paper proposes their use as the basis for incremental program testing when using test data adequacy criteria. Test data adequacy is commonly used to provide some confidence that a particular test suite does a reasonable job of testing a program. Incremental program testing using test data adequacy criteria addresses the problem of testing a modified program given an adequate test suite for the original program. Ideally, one would like to create an adequate test suite for the modified program that reuses as many files from the old test suite as possible. Furthermore, one would like to know, for every file that is in both the old and the new test suites, whether the program components exercised by that file have been affected by the program modification; if no components have been affected, then it is not necessary to rerun the program using that file.In this paper we define adequacy criteria based on the program dependence graph, and propose techniques based on program slicing to identify components of the modified program that can be tested using files from the old test suite, and components that have been affected by the modification. This information can be used to reduce the time required to create new test files, and to avoid unproductive retesting of unaffected components. Although exact identification of the components listed above is, in general, undecidable, we demonstrate that our techniques provide safe approximations.