The scope of the current body of work addresses the matter of the paradigm of the empirically derived structure(s) of psychopathology in adults. The discussion addresses how the comorbidity or the co-occurrence of symptoms influences how the nosology of mental ill health is organized and tabulated. The first part of the thesis is a systematic literature review of empirically defined models of psychopathology that have been derived using latent modeling techniques. The narrative of over 40 years’ worth of research is discussed in terms of the nosological conceptualization of how patterns of discrete mental health symptoms occur and co-occur. Specifically, efforts were made to look into the over-arching ‘multifactorial models’ of psychopathology. In the second part of thesis a concept known as the general factor of psychopathology denoted as p, that represents a statistical summary of comorbid patterns of psychological ill health is taken further and explored in a mixed sample of patient and control participants. The hope is that this work will be taken forward in support of the current zeitgeist in the fields of psychiatry and clinical psychology which favour transdiagnsotic concepts in nosology and guide research efforts into the aetiology of mental ill health and applications thereof in the clinic
