Web application software uses new technologies that have novel methods for integration and state maintenance that amount to new control flow mechanisms and new variables scoping. While modern web development technologies enhance the capabilities of web applications, they introduce challenges that current testing techniques do not adequately test for. Testing individual web software component in isolation cannot detect interaction faults, which occur in communication among web software components. Improperly implementing and testing the communications among web software components is a major source of faults. This research presents a novel solution to the problem of integration testing of web applications by using mutation analysis, "web mutation testing." New mutation operators are defined and a tool, "webMuJava," that implements these operators is presented. A series of four experimental studies was conducted using 15 web mutation operators. The results show that (1) web mutation generated very few equivalent mutants (only 6% on average across four experiments); (2) web mutation testing provides 100% coverage on web mutants whereas 12 independently developed tests designed to satisfy traditional testing criteria provides 47% coverage; (3) no traditional tests kill FOB mutants; (4) web mutation tests can help create tests that are effective at finding web faults; (5) tests designed for web mutation testing detects all kinds of method-level Java mutants; (6) tests designed for method-level Java mutation testing missed all FOB, WCTR, and WSIR mutants; (7) Java mutants help design tests that verify individual web components whereas web mutants help design tests that verify interactions between web components; (8) while overlapping, web mutation testing and method-level Java mutation testing are complementary and can improve the quality of tests; (9) three mutation operators that are redundant and can be excluded from the testing process with minimal loss in fault detection are WFUR, WHID, and WLUD; and (10) the FOB and WSIR operators may be particularly strong and can lead to high quality tests. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]