Parallel architectures offer new challenges in program complexity and design, and significantly complicate the debugging process. The increased complexity of expressing concurrency has made debugging parallel programs even harder then debugging sequential programs. Applications ruuning on KAICUBEII, a distributed-memory message-passing hypercube multicomputer, are composed of multiple processes being executed concurrently on different node computers. Debugging such applications with traditional sequential debuggers is inadequate. This thesis describes the design and implementation of a source level symbolic parallel debugger aiding KAICUBEII programmers to debug concurrent applications. The prototype debugger Kdb is implemented by extending one-process debuggers to the situation under concurrent multiple application processes. Kdb enables the programmer to use high-level symbolic references during debugging concurrent KAICUBEII application programs written in C. The parallel debugger Kdb supports not only the major capabilities found in advanced source level sequential debuggers but also the challenges derived from the distributed nature of parallel applications.