Bullying is a salient challenge for children and schools around the world, appearing to be especially prevalent at the middle-school level. Contemporary research reveals an exigent need for systematic programming that is grounded in a social-ecological perspective and aims to reduce and prevent bullying via promoting knowledge, awareness, and attitudes that facilitate the development of positive peer relationships among students. Considering this, the present quasiexperimental study examined the effects of a brief, film-based bullying prevention program, Promoting Positive Peer Relationships—Classroom Resource (P3R-CR), on middle-school students’ general attitudes toward bullying and perceptions of their school bullying supports, as a function of both general intervention as well as intervention implementation duration (1-week, 5-week, or 8-week iterations). Overall, results of the present study revealed statistically significant enhancement of general attitudes toward bullying and perceptions of school bullying supports for intervention-group students compared to control-group students, although these between-group differences were characterized by small effect sizes and were thus considered educationally unremarkable. Furthermore, social validity outcomes indicated that the P3R-CR was implemented with adequate fidelity and that its goals, procedures, and outcomes were perceived as appropriate, feasible, and effective within the local school and classroom contexts. The meaning and implications of these results are discussed and possible confounds, limitations, and future directions for bullying intervention scholarship are considered.