An increased sense of responsibility has been identified in obsessive-compulsive disorder (OCD) where patients evaluate their thoughts in terms of the harm they could cause to themselves or others. This study investigated whether a difference could be demonstrated between groups of obsessional-compulsive patients (n=26), anxiety controls (n=13) and non-clinical controls (n=25) on responsibility measures. This would support the role of excessive responsibility in OCD and encourage the use of such measures to target appropriate beliefs in therapy, to inform on progress in therapy and to predict outcome. A set of questionnaires which included general measures of psychopathology, symptom measures specific to OCD and cognitive measures (of cognitions identified in obsessive-compulsive patients) were given to the three groups and results compared. It was hypothesised that obsessive-compulsive subjects would differ from the other groups on symptom measures, on responsibility appraisals and on responsibility assumptions, but in this last category there would be more convergence between obsessive-compulsive and anxious S's as they would share some of these more general beliefs. One-way analysis of variance confirmed all three hypotheses. An exploratory factor analysis was also carried out. Factors which emerged from analysis of the three cognitive measures were appraisal of self as a source of harm, need to protect others, intolerance of ambiguity, thought/action fusion and perfectionism. These factors correspond with the domains of beliefs identified by the International OCD Beliefs Working Group (1996). Results are discussed in the context of the role of responsibility in OCD and implications for measurement, therapy and future research are identified.