Community Wireless Networks (CWNs) have recently emerged as a top priority for many communities world-wide to access the information highway and bridge the digital divide. There are many factors that contribute to the development and the sustainability of a successful CWN. These factors include traditional technical network parameters in addition to several social and economic parameters. This paper proposes a two-graph model for describing CWNs. The proposed graph model uses well established graph concepts to depict the key factors needed to be addressed when analyzing and designing CWN. We show how the two graphs; the social network graph and the wireless network graph are used to model CWN factors. We also show how the proposed model was used in a case study to support the Omaha Wireless project. We argue that having such a quantitative model represents a significant step towards better understanding of CWN and advancing this timely research area.