The reduction of particulate emissions from diesel engines is of major interest, considering the strict emission standards posed by the legislation worldwide. Although the technology of particulate filters has been under development for more than 20 years, considerable technological challenges remain regarding effectiveness and durability. The emergence of the continuous regenerating trap (CRT) in conjunction with the availability of low-sulfur diesel fuel represents a promising solution, especially for heavy-duty engines. In the present paper, a modeling approach for the combined catalyst and diesel particulate filter system is presented. The model is used to understand the main behavior trends of the oxidation catalyst and the NO2 regenerated trap individually and as a system. Illustrative model applications are also presented for the case of a modern heavy-duty engine and operating conditions corresponding to the European testing procedures. Although the model is based on global reaction schemes, it is useful in explaining the parameters affecting the CRT system behavior in the real world. Such engineering models are expected to support the selection and design of CRT systems, minimizing the testing effort.