The word manipulation is frequently applied to some of the difficult-to-manage behaviours of the personality-disordered patient. However, the term is rarely defined, and a review of both the clinical and research literature shows that little has been written about its definition and identification, let alone its clinical management in both in- and outpatient settings. Recent empirical work conducted with nurses in forensic settings has demonstrated the range of behaviours that professionals refer to as ‘manipulative’, thus clarifying the use of the term and allowing the provision of a more precise definition. The scope of manipulation in everyday life, management practice and politics is perhaps relatively small, although manipulation can occur in all areas of human activity. Social behaviour is doubly ambiguous with respect to judgements of manipulation, as such judgements involve a moral evaluation combined with the identification of deception on the basis of little or partial evidence. The implications of this social ambiguity for clinical psychiatric practice are that professionals need to guard themselves from two polar faults: seeing manipulation everywhere; or being blind to its presence. In order to achieve a cautious moderation, staff need to hold both alternatives in mind at all times.