In the wake of a severe economic crisis in the 1980s Costa Rica abandoned an import substitution model of development adopted in the 1960s and implemented policies supporting foreign investment and the diversification of its exports. This study presents an application of the model proposed by Herzer and Nowak-Lehnmann to test the hypothesis that export diversification has contributed to economic growth in Costa Rica via externalities of learningby- doing and learning-by-exporting over the period of 1965–2006. After using the autoregressive distributed lags and dynamic ordinary least squares models no long-run relationship was found between export diversification and growth.