The dissertation deals with the influence of social networking sites on their members. The publication focusses on a differentiation of various usage patterns and social mechanisms taking place on these digital platforms. Based on a structured literature analysis, first, the current state of the art is analyzed. Subsequently, the author investigates two social mechanisms theoretically and empirically, respectively. On the one hand, she analyses how social networking sites can increase belongingness needs of adolescents and thereby their subjective well-being through the usage of directed communication features. On the other hand, the role of envy feelings among students following the consumption of social information on social networking sites is investigated. In a nutshell, the results show the importance to differentiate between usage patterns, because they are linked to various social mechanisms related to controversial outcomes for users. To predict the influence of social networking site use on its members a differentiation of usage patterns is useful.