High efficiency heating, ventilation, and air-conditioning (HVAC) equipment requires proper design and sizing to ensure benefits to the customer and utility including performance, efficiency, and comfort. Utilities, states, and training providers across the Northeast and Mid-Atlantic are equipping contractors with the skills needed for high-quality installations of cold climate air source heat pumps (ccASHPs). This resource provides recommendations for improving contractor training content and delivery related to ccASHP sizing and design.