Scaling up community-based access to injectables (CBA2I) and other community-based family planning services is a promising approach to expanding access to contraceptive care on a large scale. The broad term scale-up encompasses several different paths to expansion of a successful innovation.

• Spontaneous scale-up occurs when an innovation addresses a strongly felt need within a program or community and is unsystematically shared among individuals or adopted from the pilot community to other settings. Because effective scale-up nearly always requires careful planning and implementation, spontaneous scale-up is rarely successful.
• Horizontal scale-up, also referred to as expansion or replication, describes instances when innovations are replicated in new geographical locations or expanded to serve larger or additional populations. A key factor in the success of horizontal scale-up efforts is balancing the need to adapt the innovation to new contexts while maintaining fidelity to the original innovation.
• Vertical scale-up refers to the political, legal, and institutional scale-up of an innovation. Vertical scale-up involves the adoption of an innovation on a national or regional level, whereby policy change, legal action, and systemic and structural changes are made to support sustainable scale-up of the innovation.
• Finally, functional scale-up, also termed diversification or grafting, occurs when new interventions are tested and added to an existing package of services.