This paper explores the role of William J. Baumol in the New Welfare Economics debate and the legacy of welfare economics on his subsequent works. Baumol was an extremely eclectic scholar. He was admitted as a master student at LSE in 1947, becoming a Ph.D. candidate and a member of the faculty after few weeks. His supervisor was Lionel Robbins and being at LSE put him at the center of the New Welfare Economics debate. This debate was, in the 1940s, a war between institutions and scholars, across the two sides of the Atlantic Ocean. Baumol began in fact his academic career writing on welfare economics and economic dynamic. However, after the 1970s and definitively after the 1980s, the welfare economics theoretical debate faded away and also faded Baumol’s production in this field. We argue that his interest for this branch of economics was rooted in his personal beliefs and convictions and that it left a legacy on his interest for specific topics. Coherent with his conception of economics as an applied science, his interest for welfare analysis shifted from the theoretical analysis to the applied one. Particularly in his first book, we find the awareness of a series of topics that will become his objects of study, like for example: the rising costs of services, the decline of cities and the regulation or deregulation of utilities.