We investigated adolescent prosocial relations by examining social networks based on the question “Who helps you (e.g., with homework, with repairing a flat [bicycle] tire, or when you are feeling down?).” The effects of individual characteristics (academic achievement, symptoms of depressive mood, and peer status) on receiving help and giving help were examined, and we investigated the contribution of (dis)similarity between adolescents to the development of prosocial relations. Gender, structural network characteristics, and friendship relations were taken into account. Data were derived from the Social Network Analysis of Risk behavior in Early adolescence (SNARE) study, and contained information on students in 40 secondary school classes across 3 waves (N = 840, M age = 13.4, 49.7% boys). Results from longitudinal social network analyses (RSiena) revealed tendencies toward reciprocation of help and exchange of help within helping groups. Furthermore, boys were less often mentioned as helpers, particularly by girls. Depressed adolescents were less often mentioned as helpers, especially by low-depressed peers. Moreover, lower academic achievers indicated that they received help from their higher achieving peers. Rejected adolescents received help more often, but they less often helped low-rejected peers. Last, low- and high-popular adolescents less often helped each other, and also high-popular adolescents less often helped each other. These findings show that (dis)similarity in these characteristics is an important driving factor underlying the emergence and development of prosocial relations in the peer context, and that prosocial behavior should be defined in terms of benefitting particular others.