Special observation is a common nursing activity in psychiatric units, involving intensified observation and assessment of patients deemed at risk of harming themselves or others. The activity is problematic because it inevitably violates patient rights, despite the humanistic basis of nursing philosophies and the consumerist ethos of modern health services. Nonetheless it is a poorly researched phenomenon and there is little information on which to base training and skill-mix decisions. A grounded theory study was therefore carried out in one in-patient unit, concentrating on the special observation of suicidal patients. Data was gathered from semi-structured interviews with nursing staff. Nine conceptual categories were derived, based on the ambivalent core categories of controlling and helping. On the basis of this study it is recommended that policy documents in units with similar problems be reviewed to promote individualized care plans rather than rigid protocols. Further, policies should recognize the central role of the nurse in the procedure, and ensure that the patient's named nurse assumes responsibility for implementation, including supervision of the numerous staff usually involved. Training programmes should be introduced, taking account of the range of skills and knowledge demanded by the procedure and the need for systematic assessment of suicidal patients.