Dependable systems is all about setting up controls to ensure maximum security, reliability, and safety in engineering and technology. With the increased use of computerized controls in airliners, manufacturing plants, and nuclear power stations, the topic is a significant one for computer scientists and engineers. These are the edited proceedings of the first international conference on the Mathematics of Dependable Systems, which took place at Royal Holloway, University of London in 1993. The goal of the conference was to identify unifying mathematical schemes for safety and security to enable interaction of ideas from different fields. Contributions from active researchers focus on safety-critical systems, software testing and reliability, computer security, entity authentication, formal methods, and fault tolerance.