South-South and triangular cooperation (SSC and TrC) have become key components of global development discussions and are set to play an important role in achieving the Sustainable Development Goals (SDGs). UNICEF Brazil has included SSC as a central element of its country programme (2012-2016) and has created a dedicated unit to implement it. This study systematizes key lessons from UNICEF Brazil’s experiences and seeks to support knowledge sharing and improve UNICEF’s understanding of the strategic value of SSC. It explores the perspective of partners in Brazil and in other developing countries engaged in UNICEF’s Trilateral South-South Cooperation (TSSC) programme.The study shows that several countries are advancing their social protection agenda, creating new policies and programmes and restructuring related systems thanks to technical inputs arising from TSSC. The report synthesizes the main lessons learned, specifically the successes and challenges faced by UNICEF’s TSSC.