The International Development Association (IDA) (French: Association internationale de développement) is an international financial institution which offers concessional loans and grants to the world's poorest developing countries. The IDA is a member of the World Bank Group and is headquartered in Washington, D.C. in the United States. It was established in 1960 to complement the existing International Bank for Reconstruction and Development by lending to developing countries which suffer from the lowest gross national income, from troubled creditworthiness, or from the lowest per capita income. Together, the International Development Association and International Bank for Reconstruction and Development are collectively generally known as the World Bank, as they follow the same executive leadership and operate with the same staff.

The association shares the World Bank's mission of reducing poverty and aims to provide affordable development financing to countries whose credit risk is so prohibitive that they cannot afford to borrow commercially or from the Bank's other programs. The IDA's stated aim is to assist the poorest nations in growing more quickly, equitably, and sustainably to reduce poverty. The IDA is the single largest provider of funds to economic and human development projects in the world's poorest nations. From 2000 to 2010, it financed projects which recruited and trained 3 million teachers, immunized 310 million children, funded $792 million in loans to 120,000 small and medium enterprises, built or restored 118,000 kilometers of paved roads, built or restored 1,600 bridges, and expanded access to improved water to 113 million people and improved sanitation facilities to 5.8 million people. The IDA has issued a total US$238 billion in loans and grants since its launch in 1960. Thirty-six of the association's borrowing countries have graduated from their eligibility for its concessional lending. However, nine of these countries have relapsed and have not re-graduated.