Cass R. Sunstein – a Socially Committed Constitutional Thinker. This paper reviews the work of Cass R. Sunstein who is a renowned and widely quoted legal scholar and a very prolific writer on a wide range of subjects. I outline herein some themes and ideas expressed in over a dozen C.R. Sunstein’s books that were published between 1993 and 2017. As the title suggests, an emphasis is placed on issues of constitutional relevance. Aiming to place Sunstein’s body of work within a larger context I trace a considerable shift in his approach to political problems and challenges from a purely legal to a more nuanced and multi-dimensional one. Accordingly I present Sunstein’s views on such issues as the partiality of constitutions, incompletely theorized agreements, judicial minimalism, the ideological component of judging, the cost of rights, and group polarization. The works of this contemporary Publius show that pursuing constitutional law in a practical way is much more than study in linguistics or compiling a constitutional court’s decisions. Cass R. Sunstein’s extensive oeuvre provides a rich material for devising new constitutional solutions to real social problems.