Abstract Since the mid-1950s, John McCarthy has made seminal contributions to a remarkably diverse range of important areas in computer science. In this report, we examine several of these contributions: As one of the fathers of artificial intelligence, he originated the logic-based paradigm of artificial intelligence (AI) research, arguably both the most productive approach to AI problems to date and the most promising for the future. He invented the time shared use of computer systems for the interactive development of software, a technique that allowed a single computer of large capacity to appear to a large number of simultaneous users as if that machine were theirs alone. He invented the LISP programming language, creating a program language design for the first time that was based on mathematical foundations rather than a partial abstraction away from the underlying computer hardware. The practical impact of his work has been enormous. Functional programming languages, of which LISP was the first, remain widely used, and the programming language constructs he invented remain the basis of modern programming control structures. The notion of time sharing, which he invented, remains a principle paradigm for the use of large computers even today. McCarthy's use of logic was among the primary intellectual sources of logic programming and automated theorem proving, and of many of their important applications.