This chapter describes current efforts to put the Paris Declaration on aid effectiveness into practice, with a particular focus on health. Lessons are also drawn from aid effectiveness work in support of key development priorities such as gender equality, environmental sustainability and human rights. Health is a complex sector that exhibits all of the challenges captured in the Paris Declaration. It is also at the forefront of the debate on aid effectiveness, with health donors and partner countries working to put the Paris principles into practice. Many challenges remain: i) focusing on results and developing capacities to assess progress; ii) focusing on ownership and making sure that countries, including civil society, are engaged in the design and implementation of initiatives; iii) focusing on collective action that builds on the comparative advantage of each partner; iv) paying attention to countries in fragile situations where sustained, harmonised and coordinated aid is essential.