Abstract: In this paper, we show that there exists a special breed of firms that are active in both ordinary and processing exports. Contrary to the existing literature that describes processing firms as inferior, these mixed firms are superior to other firms in multiple dimensions, and are instrumental in driving China’s export boom in 2000-2006. We show that pure processing and pure ordinary firms specialize in different stages of production such as manufacturing and R&D respectively, whereas mixed firms engage in multiple activities due to their higher ability. These firms export a larger variety of products to a larger number of destinations, and hence we call them super processors. To match these stylized facts, we build on Antras et al. (2017) and Bernard et al. (forthcoming) to develop a model of firms that are heterogeneous in their blueprint quality and manufacturing ability. In this model, firms optimize their production and sourcing behavior, and this generates the specialization pattern among different types of firms that we observe in the data. Then, based on the model’s predictions, we evaluate China’s expansion of export processing zones in 2000-2006 on the adjustments of processing and ordinary firms.