He became a junior faculty member in Cornell University Physics Department in 1963. He became a full professor in 1970. In 1974, he became the James A. Weeks Professor of Physics at Cornell. He was a co-winner of the Wolf Prize in physics in 1980, together with Michael E. Fisher and Leo Kadanoff. He got the 1982 Nobel Prize in Physics for combining quantum field theory and the statistical theory of critical phenomena of second-order phase transitions. In other words the prize was for his constructive theory of the renormalization group. In this theory he gave not only important, and even numerical, insights to the field of critical statics and dynamics in statistical physics, but indirectly also basic answers to the question: "What is quantum field theory?" and "What does renormalization mean?". He also gave a constructive answer to another important "renormalization" problem from solid-state physics, the Kondo effect.