Illegal drug abuse, in addition to excessive use of legally prescribed medications for treating mental disorders, lead to harmful consequences associated with severe health issues which raise a crucial question of national and international politics of psychoactive substance abuse suppression. Therefore, concurrent substance-related disorders and mental illnessess often result in a severe clinical condition and associated social difficulties in various aspects of a person’s everyday life. Consequently, careful consideration of such problems and addressing them is imperative. This paper, in addition to other related issues, considers causal relations between psychological disorders, and disorders caused by drug abuse by means of risk factor analysis. The aim of this paper is to provide a systematic review of characteristics of specific psychological disorders in comorbidity with problem drug use, a brief review of diagnostic instruments and quality of health care system for individuals diagnosed by dual disorders in the European Union. The paper consists of the analysis of previous research pertaining to dual disorders across the European Union and beyond. The collected data indicate a considerable presence of dual disorders in the addict population, especially within marginal groups, as well as the importance of the overall evaluation of biopsychosocial characteristics of patients under treatment. Analyzing the conditions of diagnostic instruments usage in order to determine dual diagnosis enables establishing a variety of models in which social pedagogues meet those conditions in institutions where employers allows it. Regarding the dual disorder treatment, theoreticians and practitioners have not reached consensus on the models of good practice yet related to either pharmacological or/and psychosocial treatment. However, recent researches and understanding indicate the necessity of implementing an integrative approach to the treatment within which both pharmacological and psychosocial interventions should be used. Considering the fact that overall knowledge of dual disorders in addicts are insufficient, in Croatia they almost do not exist particularly, hence there is a necessity for further investigation in this area for the sake of development of the already existing preventive and treatment guidelines.