Gas production from shale reservoirs has led to an era with a new source for energy. Like many other exploration and production activities, uncertainty and risk in developing shale gas reservoirs are quite significant. Although many reservoir characterization efforts have been made to help understand shale gas reservoirs, a systematic reservoir modeling–based approach appears lacking in the literature. This chapter presents a methodology to integrate various sources of data for characterization and modeling of shale gas reservoirs, including seismic, geologic, borehole image, conventional well-log, hydraulic fracturing treatment, and microseismic data. An integrated reservoir characterization workflow enables uncertainty analysis and quantification, including multidisciplinary integration for better characterization of reservoir properties, experimental design to rank most critical parameters and dynamic reservoir simulation for probabilistic production forecasting. Such an integrated workflow is efficient in capturing main characteristics of shale gas reservoirs and offers a quantitative means for optimizing developments of these fields.