Three groups were identified using best-friendship nominations at two time points surrounding the transition to middle school (Time 1: Spring of 5th grade; Time 2: Fall of 6th grade): (i) children who had no best-friendship at Time 1, but had a best-friendship at Time 2 (best-friendship gain; N=109); (ii) children who had no best-friendship at either Time 1 or 2 (chronically best-friendless; N=105); and (iii) children with a best-friendship at both Times 1 and 2, but with different peers at each time (best-friendship change; N=120). Peer nominations of social behaviors and victimization were collected at Times 1 and 2. Findings suggest that attraction to similar others, in addition to increased displays of prosocial behaviors, facilitate the formation of new best-friendships for both initially best-friendless and best-friended children.