This monograph reflects the results of the study of socio-psychological characteristics of co-dependence and its impact on the personal characteristics of co-dependents. Based on the analysis of theoretical and methodological bases of social and psychological peculiarities of co-dependency and applied empirical studies of personality traits of co-dependent persons the authors study factors and laws of addictive behaviour development, its characteristics and types. Psychodiagnostic methods of studying personality traits of co-dependent persons offered in the monograph let deeply study and understand factors, regularities and dynamics of development of co-dependency and build rehabilitation and correctional work taking into account these traits. We hope that the monograph will be useful and interesting for psychologists, psychotherapists, specialists in the field of addiction and co-dependent behaviour.