Abstract
This paper presents a case-study of the controversy in experimental physics which followed the contentious observation of a novel entity - a magnetic monopole. The debate about the validity of the monopole experiment ranged over both its instrumental foundation and its interpretation, and was structured at both levels by the attempts of participants to maintain prior agreements concerning the validity of other experiments. These prior agreements were constituted within a framework of theoretical concepts of the natural world which served to 'transmit' agreements from the context of one experiment to another. The monopole debate was therefore conducted within a circumscribed field of socially-accepted concepts. The implications of this debate are discussed, both for our understanding of science, and for future sociological research.