Social work's notion of environment and its environmental responsibilities have always been narrowly defined. The profession has tended to either neglect natural environmental issues or accept shallow ecological conceptualizations of nature as something other, quite separate from the human enterprise and/or outside the reach of social work activity. The Biophilia Hypothesis, first articulated by then Harvard evolutionary biologist E. O. Wilson in 1984, offers social work an fundamentally different view of the person/environment construct and argues for a primary shift in the way the profession views its relationship with the natural world. This article traces the conceptual development of Biophilia theory and reviews pivotal empirical evidence explicitly arguing for the