Breastfeeding (BF) promotion is one of the most cost-effective interventions to advance mother–child health. Evidence-based frameworks and models to promote the effective scale up and sustainability of BF programs are still lacking. A systematic review of peer-reviewed and gray literature reports was conducted to identify key barriers and facilitators for scale up of BF programs in low- and middle-income countries. The review identified BF programs located in 28 countries in Africa, Latin America and the Caribbean, and Asia. Study designs included case studies, qualitative studies, and observational quantitative studies. Only 1 randomized, controlled trial was identified. A total of 22 enabling factors and 15 barriers were mapped into a scale-up framework termed “AIDED” that was used to build the parsimonious breastfeeding gear model (BFGM). Analogous to a well-oiled engine, the BFGM indicates the need for several key “gears” to be working in synchrony and coordination. Evidence-based advocacy is needed to generate the necessary political will to enact legislation and policies to protect, promote, and support BF at the hospital and community levels. This political-policy axis in turn drives the resources needed to support workforce development, program delivery, and promotion. Research and evaluation are needed to sustain the decentralized program coordination “gear” required for goal setting and system feedback. The BFGM helps explain the different levels of performance in national BF outcomes in Mexico and Brazil. Empirical research is recommended to further test the usefulness of the AIDED framework and BFGM for global scaling up of BF programs.