Summary In this paper, two relatively new science-based technologies—biotechnology and nanotechnology—are assessed to determine whether they provide windows of opportunity to less developed countries (LDCs) for catch up. By examining international patent and firm foundation trends in both industries, we found that Brazil, China, and India have jumped into these two potential catching up technologies. The paper turns to a discussion of the approaches to overcoming entry barriers that have been successful in this context and also describes why only a few countries are currently in a position to take advantage of them to facilitate catching up.