A programme of research into conflict (e.g. violence, absconding, medication refusal) and containment (e.g. seclusion, special observation, physical restraint) in inpatient psychiatry has been under way at City University, London, UK, for the past 10 years. Recent research findings, plus the challenges posed by ongoing projects, have made apparent the need for greater clarity about the overarching concepts of 'conflict' and 'containment'. This paper pulls together research findings pertaining to this issue, and conducts a reasoned analysis of what common characteristics might underlie 'conflict' and 'containment'. It is concluded that these are patient threats to safety, and the staff maintenance of safety. Details are presented on the inclusions and exclusions that follow from taking such a position, and potential definitions offered. On the grounds of this conceptual analysis, plus evidence for moderate degrees of statistical association between behaviours and events in each domain, it is concluded that it is legitimate to conduct analyses at the level of total conflict and containment rates, as well as at the level of individual types of behaviours and events (e.g. verbal abuse, sedation). Some of the mathematical difficulties in the analysis of total conflict and containment are addressed, and results of a weighting exercise presented. This exercise challenges our perception of the severity of some containment measures that are becoming more commonly used in acute psychiatry.