The passing of the eminent American Catholic economist, Dr. Rupert J. Ederer, at the age of ninety on Thanksgiving Day 2013 calls attention to the great, but equally unsung, economic thinker and system that he devoted most of his career to furthering: Heinrich Pesch, S.J. and solidarism. Pesch, who died in 1926, was thought to have inspired Pope Pius XI’s great social encyclical Quadragesimo Anno five years later. In spite of Pesch’s relative obscurity, Ederer called him an economic “system builder,” on par with Adam Smith, Karl Marx, and John Maynard Keynes—although the system he constructed was based firmly on Catholic teaching and the natural law. The word “solidarism” rings of the principle of solidarity, which has been stressed more recently in Catholic social teaching. In fact, solidarism is also referred to as “the solidarity work system.” There is some indication that Pesch’s solidarism influenced the famed Solidarity trade union movement in Poland that rose to prominence a generation ago and led the way to the collapse of Eastern European communism.