Traditional approaches to education and youth work were transformed by two psychologists who came to the United States as Hitler rose to power. Practical theorist Kurt Lewin challenged mechanistic ideas of behavior by studying children in their natural "life space." Theory practitioner Fritz Redl applied life space concepts to work with troubled children. The reclaiming youth movement sprang from these pioneers and their proteges. The landmark work on troubled children and youth is "The Aggressive Child" by Redl and David Wineman. This is a carefully documented account of highly troubled children in an experimental program called Pioneer House in Detroit, Michigan. At the 50th anniversary of this book, Larry Brendtro and the author undertook research on the roots of Redl's philosophy and its legacy of programs for troubled youth. They both had the opportunity to know Redl and Wineman directly through their early professional experience at the University of Michigan Fresh Air Camp. However, they had not anticipated the extent to which progressive programs for challenging youth can be traced to the intellectual genealogy of Redl and his colleague Lewin. (Contains 7 endnotes.)