The protective role of friendships in middle school is well established, yet no research to date has examined how to build friendships among middle school peers. In the present research, we adapted the Fast Friends procedure for inducing interpersonal closeness to promote friendships among students (n = 301) in middle school. Given the growing diversity in the K-12 population and the benefits of cross-ethnic friendships for ethnic majority and minority youth, we examined whether the intervention was equally effective at fostering same- and cross-ethnic friendships. Results indicated that the intervention successfully increased interpersonal closeness and friendships for participants in both same- and cross-ethnic conditions. Implications for using Fast Friends to promote the healthy social development of adolescent youth are discussed.