BCPL is a simple systems programming language with a portable compiler that has been implemented on many machines from large mainframes to mini computers and microprocessors. The book provides an introduction to the language, paying particular attention to programming style. In addition, it covers the more machine-independent parts of the BCPL library and outlines various debugging aids that most implementations provide. The syntax analysis phase of the compiler is described in detail, giving a realistic example of a typical application of the language. This and other substantial examples given in the book will be of interest both to serious users of BCPL and to computer writers. There is a chapter concerned with the portability code generator design. The reference for BCPL appears as the final chapter.