Costa Rica was one of the first countries in the Latin America and Caribbean region to choose the World Bank Program for Results (PforR) financing instrument to support the implementation of the Strategic Agenda for Strengthening Health Insurance by the Costa Rican Social Security Fund (CCSS), for its name in Spanish, Caja Costarricense de Seguro Social). The PforR's unique features include using a country's own institutions and processes and linking disbursement of funds directly to the achievement of specific program results, which helps building capacity within the country, enhances effectiveness and efficiency and leads to achievement of tangible, sustainable program results. The CCSS is the primary provider of health care in the country. The PforR "Strengthening Universal Health Insurance in Costa Rica" was approved by the World Bank's Board of Executive Directors in 2016, with the aim of improving the availability and quality of the universal health insurance system while boosting the institutional efficiency of the CCSS. Through the PforR, the CCSS successfully undertook strategic and complex health sector reforms that have had significant impact on quality of care, equity, and efficiency in Costa Rica's health sector. This series of knowledge reports, developed by the World Bank in collaboration with the CCSS, aims to document the drivers of success, how challenges were faced, and crucial lessons learned during the design and implementation of the PforR and its associated transformative reforms. The overarching objective is to provide a practical guide for other countries interested in implementing similar programs.