While many characteristics of patients, professionals and facilities with relevance to seclusion rates have been investigated, their relative importance is unclear. Virtually no attention has been paid to team processes and reflexivity in relation to decision making on seclusion. The aim of this paper is to estimate the effects of these factors on nurse decision making on seclusion. Sixty Dutch psychiatric nurses of four closed wards reported team reflexivity and their tendency to seclude a theoretical patient. Approachability (whether there was a good or hardly any possibility to communicate with the patient), staffing level and confidence within the team had the greatest impact on the decision to seclude. Intra class correlation was 0.30. There was a large interaction effect of reflexivity with team 4, and team reflexivity was highly correlated with team tendency to avoid seclusion. In nurses' decision on seclusion, the effects of 'pure' patient characteristics are small as compared with the effects of interpersonal and contextual factors, and nurses vary widely in their judgement. Team reflexivity is related to the tendency to prevent seclusion.