In 1965, British general practitioners were asked to submit undated resignations to the British Medical Guild to be used as a threat in negotiations with the government over terms of service. This study, based on a national sample of British GPs, is concerned with comparing the doctors who responded to the call for their resignations with those who did not. Those doctors most likely to break ranks with the majority of their fellow doctors by not participating had the least investment in the issues at stake, faced the least adverse work circumstances, were most insulated from the social pressures of other doctors, and appeared to suffer the greatest conflict between the issues at hand and professional norms. The historical and organizational circumstances under which the dispute developed are reviewed.