Abstract Sectoral concentration of exports has been a longstanding matter of concern for policymakers in developing countries. According to economic theory and recent empirical evidence, improved market access through trade agreements is likely to favor export diversification. In this article, it is assessed whether this has been the case for Colombian exports to the United States and whether an FTA with the United States would help Colombia diversify their exports. We find that lower tariffs have indeed favored exports of new products from Colombia. Predictions suggest that the FTA is likely to induce further diversification, but only up to a certain point. Keywords: trade policyexport diversificationColombia Acknowledgments We gratefully thank the editor, two anonymous referees, Álvaro Andrés Perdomo, Francesca Castellani, Marcela Meléndez, Mauricio Mesquita Moreira, and Victoria Florez Toro for their helpful comments. We also thank Diana Marcela Gómez, Pedro Martínez Alanís, Paulo Rodrigues Bastos, Jerónimo Carballo, and Ramiro Pascual for their excellent research assistance. Finally, we owe gratitude to Carlos Gutierrez Jr. for his excellent editorial assistance. The views and interpretations in this document are those of the authors and should neither be attributed to the Inter-American Development Bank, its executive directors or its member countries nor to the Departamento Nacional de Planeación (National Department of Planning). Other usual disclaimers also apply.