This document summarizes evidence-based best practices for developing sustainable capacity in paraprofessionals—also known as lay health workers, community health workers, or non-specialist providers—in health and education in resource-constrained environments. Evidence indicates that the most effective way to build capacity in these settings is through a holistic, continuous model that focuses on the development of the specific knowledge and skills required for the job, including the ability to build trust, demonstrate empathy, and communicate effectively with program recipients. These elements can effectively be developed through the intervention design, training, and supervision to ensure paraprofessionals can deliver programs with quality.