On a narrow strip of land between the Mississippi River and the U.S. Army Corps of Engineers’ flood control levees in New Orleans, a squatters’ community called the Batture exhibits an unusual inversion of conventional assumptions regarding hazard awareness and development security. For a New Orleanian to willingly take up residence on the “wrong side” of the levee is to break the most fundamental rule of the city’s spatial economy and collective psychology. This article proposes the existence of a Batture Effect , a mode of insurgent citizenship whereby hidden environmental threats are made visible and small-scale architectural, urban, and psychological adaptation measures are tested. As an adaptive design strategy, organic in its development over time and responsive to the immediate needs of residents, the occupation of the Batture demonstrates a homesteader’s approach to land appropriation. In calling into question land-use and ownership, the urban planning process and its associated spatial agency, and the role of the individual in disaster preparedness, this guerilla urbanism suggests relevant lessons to the practice of landscape architecture and urban planning.