The article investigates and describes essence of social work with personnel and draws some conclusions based on a new approach to defining social work with personnel, describes scientific and theoretical foundations of the concept of social work with personnel in the organization and its main elements. It focuses on methodological foundations and identifies main elements of the methodological base of social work with personnel, defines its subjects, objects, target, goals and tasks. This study is also devoted to analysis of conformity of social work with personnel within natural laws and examines general and specific principles of social work with personnel, its general functions (ethical, prognostication, preventive, communication) and concrete functions (social security, social aid, social services, social insurance). It classifies methods of social work with personnel based on such indications as direction and forms, objects and subjects of social work. The article also deals with means of social work with personnel and describes its technologies, identifying differences between traditional general technologies (social diagnostics, social examination, social foresight, communication skills, public regulations, skills, social insurance, social adaptation, social counseling, social security), special technologies (used when dealing with workers having very young children or large families, elderly or young workers applying for a job for the first time, disabled workers) and innovation technologies. It also defines essence of management and organization of social work with personnel. The main result of the study is a proposed methodological concept of social work with personnel in the organization representing the content of the given notion.