This ethnographic study explores the perceptions of staff regarding the nursing activity of constant observation of the suicidal patient in mental health settings. Unusually, the paper also addresses the perceptions of the patients themselves, and compares the two. Two major categories of nursing interventions, Therapeutic and Controlling, were identified by both groups of respondents. However, although there was a degree of commonality between the groups' descriptions of subcategories, there are also interesting anomalies. Patients did not perceive some actions at all, one action was not perceived by staff, and one action was perceived to be in different categories by the two groups. Such differences are discussed, and implications explored.