Jos Vaessen (PhD) is Methods Advisor at the World Bank. He has been working in evaluation research since 1998, first as an academic evaluation consultant and later on as a lead evaluator. He has conducted and led evaluations for multilateral and bilateral development organizations in a range of policy fields such as agriculture, environment, science, education, health and others.

Since 2016 he has been leading the Methods Advisory Function at the Independent Evaluation Group. Jos has authored several internationally peer-reviewed publications, including three books. His most recent publication is titled Evaluation of International Development Interventions: An Overview of Approaches and Methods.