“I think that the most important question that an economist can ask is, What is it that makes a country grow? More than anything else it is economic growth that affects human welfare…this is why it must remain a major research interest for economists.” In this interview Xavier Sala-i-Martin—widely recognised as one of the world’s leading economists in the field of economic growth—discusses with Brian Snowdon several important issues relating to economic growth and development. The interview, which follows a review of the historical context of recent research, addresses arguments about growth and history, theories and models, globalisation and convergence, political barriers and the ‘natural resource curse’, the impact of religion and culture, and questions of international inequality, foreign aid, human capital, geography, competitiveness, economic and political freedom, and happiness.