The article presents the results of an empirical study, focusing on the association between self-concept clarity, online behavior and self-presentation in adolescence. The study was conducted in the framework of the research project “Digital Portrait of Contemporary Adolescents”, operated by the Center for Inter- disciplinary Research on Contemporary Childhood in Moscow State University of Psychology and Education. The data was collected in February 2020. 52 adolescents, studying in School № 27 in Mitischi (Russia, Moscow Region) took part in the survey. The following methods were used: Self-Concept Clarity Scale (SCCS, J. Campbell); The Presentation of Online Self-Scale (POSS, C. Fullwood); Face- book Intensity Scale (FIS, N.B. Ellison); Chen Internet Addiction Scale (CIAS, S.W. Chen); Online Activity Questionnaire (O.V. Rubtsova, T.A. Poskaklova). Data shows that strategies of adolescents’ interaction and self-presentation in social networks relate to their self-concept clarity. Adolescents with low self-concept clarity tend to experiment in virtual space: they often provide inaccurate information about themselves and create numerous cyber-identities. This group of adolescents is also inclined to risky online behavior and Internet-addiction. All these indicators improve with the increase of self-concept clarity. The data testifies that contemporary adolescents use social networks as platforms for experimenting (e.g. with roles), in the process of which they resolve important age challenges, related to the development of agency and formation of self-concept.