Post-Keynesian Institutionalism (PKI), a synthesis of post Keynesian and institutional economics, emerged in the USA as a strand of evolutionary economics in the early 1980s and has attracted increasing attention in recent years. This article examines milestones in the development of PKI, devoting particular attention to the tradition's conception of the role of the state. The first section identifies antecedents to PKI in the writings of John R. Commons and John Maynard Keynes. The second describes how PKI emerged against the backdrop of increasing dissatisfaction with neoclassical Keynesianism in the era of stagflation. The third summarizes the subsequent contributions of Hyman P. Minsky, whose work was a model of PKI in the 1980s and 1990s. The final two sections outline PKI's contemporary characteristics and identify elements of an agenda for future research. PKI has always been about achieving a more humane form of capitalism, which requires the state to play a creative role in shaping economic life.