The use of commercial off-the-shelf (COTS) software product can potentially reduce cost and time for software system development. But this promise is often not realized in practice because COTS product does not serve organizations? expectations. Thus, decision making on selecting COTS product becomes a critical task which should be performed in a systematic and repeatable manner. The Decision Analysis and Resolution (DAR) process area of Capability Maturity Model Integration (CMMI) provides practices for formal evaluation process which could be applied to COTS selection. However, CMMI does not describe how to conduct the process that can achieve its defined goals. This research presents the DAR on COTS Selection (DARCS) process model according to DAR process area of the CMMI. The model is consisted of three layers: core workflow layer, workflow details layer, and description layer.