To gain a better understanding of those struggling with severe eating disorders (anorexia nervosa and bulimia nervosa), the inner life-world and subjective experiences of therapy clients were explored within the South African context. This was an empirical qualitative study. Specifically, the study’s focus was on the psychological construct of perfectionism as experienced during the respondents’ treatment resistant eating disorders. The two objectives of the research were to describe and explain perfectionism, which served to increase an overall improved understanding of perfectionism. The study’s methodology encompassed a combination of phenomenological- and grounded theory methodology, exploring the narratives of six female candidates that were undergoing individual therapy for their eating disorders. These candidates were considered to have a treatment resistant eating disorder, because they had been struggling with this diagnosis for longer than a decade, and/or had previously received multiple treatment interventions without recovering. The therapy sessions were recorded via digital audio recordings, and used in the data analysis process. The discourses pertaining to the study’s focus were transcribed and analysed using phenomenological- and grounded theory methods. The phenomenological analysis produced individual descriptions of the participants’ experiences of their perfectionism, as well as a general description for perfectionism. The grounded theory analysis produced an emerging theory in the form of a cognitive schema. This schema was named The Perfectionistic Eating Disorder Self-schema (PEDSS), and explains the inner psychological process of perfectionism within a treatment resistant eating disorder client. The results of this study, in particular the PEDSS, has implications for those trying to understand, assist, and treat those who suffer from treatment resistant eating disorders, as well as helping those who struggle with perfectionism to understand their own problem more. / Psychology / D. Phil. (Psychology)