His current research projects include the Testing of Critical System Characteristics (TOCSYC) and PILOT projects at University of Skövde (Sweden), model-based testing, analysis and testing of web applications, test automation, and usable security. He was on the technical board of advisors for Certess, Inc. He leads the MS in Software Engineering program at Mason, teaches Software Engineering courses at all levels and has developed new courses on several Software Engineering subjects, including web engineering, software testing, construction, design, usability, experimentation, and analysis. As part of his research, he has invented several new coverage criteria collaborating with a team of colleagues. These criteria include base choice coverage, prime path coverage, active clause coverage, coupling-based testing, bypass testing, and inheritance & polymorphism coverage. These included analysis and modeling techniques such as atomic section modeling and finite state machine modeling for web applications, the ping-pong algorithm for test suite reduction, and OO analysis techniques based on the yo-yo graph.
His textbook, Introduction to Software Testing (co-authored with Paul Ammann), was published by Cambridge University Press in January 2008 and is the leading worldwide textbook in software testing.