There have been many changes in the way the first course in Computer Science is taught since the first edition of this book was published in 1981. During the past two years I have been the chairman of the ACM Task Force that has been studying these changes with an eye towards updating the description of the recommended first course for Computer Science majors (CSl). Parallel with this effort, the Educational Testing Service (ETS) published a set of guidelines for an Advanced Placement course in Computer Science. The text has been completely revised and reorganized to conform to both of these guidelines.