Global competition, restructuring, economic uncertainty and attempts to gain and retain talented workforce are challenges which employees and organizations have to face. These challenges affect the working environment and change the nature of the work relations. The number of newcomers requiring socialization increases steadily and organizations are more frequently challenged with the newcomers socialization process. Organizational socialization studies have been gaining more and more attraction within the last years. However, the phenomenon of newcomers socialization was mainly studied with regard to psychological aspects and outcomes and influences of newcomers team leaders. Despite awareness of organizational insider influences during organizational socialization, there is a lack of attention with regard to the influence and effects of team members and resulting social relations. This thesis reviews the literature of organizational socialization and outlines several concepts and influencing aspects of newcomers entry phase. The main aim of this thesis is to examine the interaction between newcomers and co-workers by the use of a 360 degree feedback method. In addition, the overall process was analyzed to investigate consequences of newcomers socialization processes. Results show that co-workers support can be seen as a key success factor affecting the newcomers socialization process. In addition, team affiliation was facilitated by the newcomers integration. The newcomers successful socialization led to an increased group cohesiveness, but at the same time negatively affected the groups psychological safety. The research findings are illustrated in form of a visual aid to better understand the influencing factors of the newcomers successful socialization.