This paper examines the relationship between export diversification and economic growth in Small Island Developing States (SIDS), an area for which theory has conflicting views and virtually no empirical research has been undertaken. Empirical evidence shows a significant gap in the export diversification and economic growth experience of SIDS generally, although several small nation states have managed to close the gap with respect to key indicators and successfully evolve from developing to advanced economy status, suggesting that there may be a path by which SIDS can become economically advanced. Utilizing data from 1995 to 2007 for 69 economies segmented by country classification and geography, the empirical results find a non-linear, U-shaped relationship between export concentration and economic growth. This finding is consistent with previous research and robust to different specifications of the growth equation. Further, the study finds that the U-shaped relationship is moderated by the size of the population whereby small nation states, inclusive of small island states, seem to benefit more from export diversification as compared to mid-size and large economies. The findings have noteworthy policy implications for SIDS policymakers seeking to strengthen and improve the diversification, stability and economic growth trajectory of their economies.