Nurses are increasingly using cognitive behaviour therapy as an intervention for psychological problems attached to a variety of clinical conditions. Developing both self-acceptance and self-esteem have been identified as ways to enhance cognitive interventions. However, there are disagreements about the relationship between self-esteem and self-acceptance and their influence on psychological health. The study examined the relationship between these concepts and also the association between the concepts and psychological health. Fifty-eight participants with a diagnosis of severe and enduring mental health problems were assessed recording levels of self-esteem, self-acceptance, depression, anxiety and psychological well-being. The results revealed that, in comparison with the general population, the sample were more likely to have lower self-acceptance and self-esteem, and higher levels of anxiety, depression and psychological ill health. The concepts of self-esteem and self-acceptance were found to be similar but not synonymous. Self-esteem was more closely associated with affect, with higher levels of self-esteem being indicative of lower levels of depression. Self-acceptance appeared to be more closely associated with general psychological well-being and to be more helpful when undertaking clinical work for general psychological problems.