We argue that adolescent friendships flourish, or wither, within the "linked lives" of other salient social network ties. Based on structural equation modeling with data from two time points, we find that young people tend to be in high-quality friendships when they are tightly embedded in their social network and receive social support from their peers, parents, and romantic partners. In addition, females have higher quality friendships than males, and the life course transition to marriage has detrimental effects on friendship quality. Findings show that the influence of parents does not end in childhood but continues into adolescence. Furthermore, although earlier research documents that friends affect romantic relationships, we find the reverse, that is, romantic partners influence friendships. Results demonstrate that social connectedness and support from a range of network ties contribute to high-quality, caring friendships among youth, highlighting the utility of life course and social network perspectives.