This textbook is an introduction to the design and writing of computer programs. It leads the reader through all the stages of program construction from the original specifications through to the final program. The formal verification of intermediate versions of the program is studied in considerable detail. The authors show how, given the formal specification of a program, data structure and program structure diagrams are drawn and then converted into a procedural program in a program design language (PDL). They demonstrate the conversion of PDL into a variety of real programming languages including Pascal, FORTRAN, COBOL, and Assembler. The book also includes chapters on abstract data types, analysing existing programs, and a small case study. First-year undergraduates in computer science and graduates taking courses in computing will find this a comprehensive introduction to program construction.