A review of the Project on Diverse Software (PODS), a collaborative software reliability research project, is presented. The purpose of the project was to determine the effect of a number of different software development techniques on software reliability. The main objectives were to evaluate the merits of using diverse software, evaluate the specification language X-SPEX, and compare the productivity and reliability associated with high-level and low-level languages. A secondary objective was to monitor the software development process, with particular reference to the creation and detection of software faults. To achieve these objectives, an experiment was performed which simulated a normal software development process to produce three diverse programs to the same requirement. The requirement was for a reactor over-power protection (trip) system. After careful independent development and testing, the three programs were tested against each other in a special test harness to locate residual faults. The conclusions drawn from this project are discussed.