This article tells about the founding of the Danish environmental organization NOAH in March 1969. The organization was created primarily by students connected to the natural sciences and the architecture school, and followed a spectacular happening in an auditorium at the University of Copenhagen. Central to NOAH was an “ecology-based” systemic critique and a decentralized organizational structure which the organization has adhered to for 50 years. NOAH was part of the new left culture of the 1960s and 1970s. Over the years, thousands of Danish activists have been part of NOAH, which today is a smaller organization.