Abstract Modeling the elastic properties of the Haynesville Shale using rock-physics techniques is part of the characterization of this shale that could be used to improve predictions of economic drilling locations. The goal of this modeling is to relate the reservoir properties of interest (e.g., porosity, pore shape, and composition) to the elastic properties. Although this is the same goal as in using rock physics for conventional reservoirs, the approach used here differs. Within the Haynesville Shale, the physical rock properties that most significantly affect the elastic properties appear to be the composition and pore shape. Accordingly, the rock-physics modeling requires an effective-medium theory, notably the self-consistent model, to accommodate these properties. Composition was estimated through a combination of well log and x-ray diffraction (XRD) data. Pore shapes were estimated using estimated stress conditions and numerical studies. The best modeling results explain trends in velocity measurements corresponding to joint variations of composition and pore shape. Accordingly, this rockphysics model could be used in conjunction with seismic data interpretation to identify locations with low velocity and potentially higher organic content and zones with faster velocity more suitable for fracturing.