Many B2B organizations have complex partner ecosystems and lack a common understanding of, and alignment across, the foundational elements required for success. There are three cornerstones that orient companies toward success by informing and guiding partner ecosystem strategy development and partner ecosystem programs, processes, activities, and measurements. This report introduces these essential cornerstones — partner types, partner personas, and partner journeys — and provides a step-by-step guide with ready-to-use templates to help organizations lay a strong foundation for their partner ecosystem strategy.