The paper investigates how field experimentation of genetically modified crops became central to the French controversy on genetically modified organisms (GMOs) in recent years. Initially constructed in the 1980s as a cognitive endeavor to be preserved from lay interference, field trials of genetically modified crops were reconceived as "an intrusion in the social space," which had to be negotiated with actors from that space. In order to analyze this transformation, the authors suggest that it is necessary to develop an interpretive framework that combines theoretical perspectives from science and technology studies and the sociology of social problems, and emphasizes the importance of the way in which actors compete in a heterogeneous public space, to put forward alternative framings of problems. The authors present a detailed analysis of the interactions and conflicts between actors in diverse social arenas in order to better understand the dynamics of this sociotechnical controversy.