The article deals with the problem of creating a methodology for studying interconnected processes of professional self-determination and professional career. The concept of social interconnection mechanism between social processes is offered by the author as one of these methods. This social mechanism is regarded as a stable system of conditions that acts and interacts on various levels of the social system (namely: institutional, structural and individual levels) and ensures co-occurrence of these processes. The author uses integrative approach to analyze the mechanism of social interconnections between professional self-determination and professional career. The methodological feature of the concept of “social mechanism” is defined in the course of study of interaction between professional self-determination and professional career processes, which, first, is presented by possibility to explore the interconnection between these processes as integrity, along with that highlighting levels, elements and links between them; and second, in possibility at the same time to study this interconnection considering a continuous process of transformation.