The aims of this study are twofold, firstly the study acts as a prevalence estimate for the number of dually diagnosed homeless people, and secondly, the study aims to test the hypothesis that those homeless persons with dual diagnosis have spent a longer time homeless than those homeless who are not dually diagnosed. The concept of dual diagnosis still lacks understanding, and of what we do know for certain is that facilities to help those with dual diagnosis in Ireland are severely lacking. Given the high rates of drug use, alcohol use, and mental illness among the homeless, it is logical to presume that there exists a large proportion of dually diagnosed individuals who are homeless and experience great difficulty in breaking away from homelessness. This study uses a sample of 24 homeless individuals, 17 male and 7 females. The descriptive statistics herein show that there is a large number of dually diagnosed homeless persons, but however, these individuals do not spend a significantly longer time homeless than non dually diagnosed homeless person. This study hopes to lead to further research that can have a great impact on the policies regarding preventing and abolishing homeless.