Kadanoff in the 1960s made innovative and original contributions to the understanding of phase changes, such as the change of water from liquid to ice. In later years he also helped construct a new field of knowledge called soft condensed matter physics, which deals with such phenomena as the flow of fluids and the behavior of granular materials. He has been especially interested in how complexity arises from simple phenomena, such as avalanches forming from the forces that are transmitted from grain to grain in sand. His awards include the National Medal of Science -- the nation's highest scientific honor. In 2007, Kadanoff served as president of the American Physical Society.