In Berkeley, California in the late 1960s, a number of prominent architects saw it as their responsibility, not so much to serve existing social needs as to collaborate with social forces that were in the process of an entirely new world, both physically and institutionally. These architects took their cues from ecology, systems theory, and counterculture communes, theorizing a dynamic unfolding of co-evolving social subjects, within which architectural design might join together with a radical politics of egalitarian interdependence. This paper especially focuses on the research and writing of Sim van Der Ryn between 1967 and 1971, tracing his transformation from an architect primarily concerned improving the social functions of architecture to an architect most closely identified with ecology and ecological systems. These two phases of his career, I would argue, are not as separate or disjunctive as they might first appear. Rather they are the flip sides of an ecological utopianism that emerged in the work of a number of architects around 1970, but whose original problems and meanings have been obscured in subsequent decades.