Recent evidence on world trade patterns reveals North-South specialization across products of the same industries and product groups but different quality, which is not matched by the predictions of traditional and new trade theory. This paper analyzes a model of North-South trade and endogenous growth through innovation and imitation that can predict the observed trade patterns. The model is used to re-examine the impact of trade and Intellectual Property Rights (IPR) protection on both the innovation in the North and the imitational lag of the South. Opening to trade increases the growth rate and welfare of both regions, but results in a larger lag in the quality level of the South. With free trade the quality lag of the South is positive even with no IPR protection as a result of a revealed comparative advantage in lower quality goods production and trade. This contradicts the common predictions of Southern take-over of the whole industries due to bad IPR enforcement. Stronger IPR protection has a negative effect on growth and deteriorates the lag of the South, but the welfare effects of the alternative IPR policy instruments may be different.