According to Social Identity Theory self esteem in the fundamental motivational factor for social identity. many scholars have contended that other functions beside self esteem may account for social identification. The present study investigates different functions of social identity in different types of adolescents peer groups (spontaneous, sports, religious and political groups) members of these groups rated the importance of different group functions. The factor analysis of our first set of data revealed the existence of six factors: ingroup identification, self insight and social understanding, intergroup competition and comparison, intragroups comparison, cooperation and romantic involvement. Out results shows that different groups emphasized the importance of different functions. The findings support the hypothesis that group memberships can serve a variety of identity functions, several of which are not considered by the SIT. Furthermore the results display a lack of correlation between ingroup identification and intergroup competition and comparison .