A qualitative examination was undertaken of an abstinence-based treatment programme for those with drug addiction in a Therapeutic Community in Dublin. The primary sources of data were the clients who are currently engaged in the programme, the staff who are currently employed within the Therapeutic Community and a Consultant Psychiatrist who is the clinical advisor to the centre. Qualitative research was carried out in order to gather opinions from both the clients and staff in the community with regard to the suitability of the Therapeutic Community Model of treatment for those with a dual diagnosis. Information was also gathered as to how such a programme may be modified to provide effective treatment to such clients. The questionnaire was designed thematically in order to examine participant's attitudes on the subject matter in relation to their own personal experiences of addiction, mental health issues and the Therapeutic Community Model. The results obtained reflected the programme in a very positive light and as a suitable treatment option for those with a dual diagnosis. In particular the results highlighted the need for further training of staff in the area of mental health and the modification of the current programme to provide an optimal integrated treatment approach for clients with dual diagnosis. The literature reviewed considered the current lack of suitable treatment options available for those with a dual diagnosis in Ireland and the poor management of those presenting with such a disorder to various addiction and mental health services. It considered the theories of causation of dual diagnosis, clinical responsibility and optimal treatment approaches, including that of the Therapeutic Community Model. The discussion focuses upon the themes of the interviews and issues arising from the respondent's experience and opinions, in particular the need for modification of the therapeutic community model; these are then related to relevant theoretical opinions on the subject of dual diagnosis.