The purpose of this research was to explore how the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) 1994, (American Psychiatric Association, 1994) defines mental disorder and the theoretical assumptions upon which this is based. The analysis examines how the current definition has been constructed and what the criteria for specific mental disorders suggest about what is regarded as normal. The method employed for the research was a critical discourse analysis. This critical approach to research is primarily concerned with analysis of the use of language and the reproduction of dominant belief systems in discourse. It involves systematic and repeated readings of the DSM-IV (1994) to examine what evidence was employed by the text to substantiate its definition of mental disorder and how in the process some assumptions are made about what constitutes normality. This study challenges a central assumption in the DSM-IV’s (1994) definition: that it is a pattern or syndrome ‘that occurs in an individual’. The proposal that it occurs in an individual implies that it is a consequence of faulty individual functioning. This effectively excludes the social and cultural context in which experiences occur and ignores the role of discourse in shaping subjectivity and social relations. This study proposes that the definition and criteria for mental disorder are based on assumptions about normal behaviour that relate to productivity, unity, moderation and rationality. The influence of this authoritative image of normality pervades many areas of social life and pathologises experiences that could be regarded as responses to life events.