Computable general equilibrium (CGE) modeling is an attempt to use general equilibrium theory as a tool for analysis of resource allocation and income distribution issues in market economies. Since the beginning of the 1990s, CGE modeling has been widely used for analysis of environmental policy and natural resource management issues. The purpose of this chapter is to review this branch of CGE modeling.Most existing CGE models are static, but as faster computers and more efficient software have become available, an increasing number of environmental CGE models are dynamic. In addition to the static-dynamic dimension, it is useful to distinguish between single-country, multi-country and global models. Some environmental CGE models are primarily focused on the external effects of production and consumption, while others are designed to elucidate various issues related to the management of natural resources.However, most existing CGE models are focused on externalities, primarily emissions of greenhouse gases. Global "externality" CGE models have been used to estimate the social cost of complying with the Kyoto Protocol, while single-country models, among many other things, have been used for evaluation of the efficiency of emission taxes and other environmental policy instruments.CGE modeling currently is both a field for specialists and an almost standard part of the toolbox of economists concerned with policy-oriented research. A major reason for the widespread use of CGE modeling probably is that a CGE model is an ideal bridge between economic theory and applied policy research. The "bridge" perspective, however, suggests that CGE modeling is a way of using rather than testing economic theory. Yet carefully designed and estimated CGE models have a lot to say about real world economies.