Purpose-The aim of this piece of research was to detail the scope and nature of sectarianism as experienced by employees, managers and those with trade union responsibilities, in the Northern Ireland workplace. Design/methodology/approach-Four large organizations, two from the private and two from the public sector, were recruited to take part in this qualitative study. In-depth inter-views were carried out with managers and trade union personnel. Focus groups were run with employees. Findings-Data were submitted to thematic analysis. The major themes to emerge included: the extent of experienced sectarianism, sources of sectarianism, the nature of sectarian harassment, ``tolerable'' sectarianism, and the management of difference. Research limitations/implications-Short-comings of the study include the possibility that social desirability effects could have operated to underplay sectarian attitudes. Again the limitations of a qualitative methodology in providing estimates of the extent of sectarianism in the broader population are acknowledged. Practical implications-Practical implications of the findings for controlling sectarianism and managing diversity are discussed in terms of organizational formalization, the promotion of a common ingroup workforce identity, and the informal procedures used by employees to manage difference on a day-to-day basis. Originality/value-The study is particularly pertinent, given that there has been little attempt to capture the experiences of sectarianism in workplaces from the perspective of managers, employees and trade union personnel.