This paper serves as documentation for the General Equilibrium Model of Ecosystem Services (GEMES). GEMES is a regional computable general equilibrium model that is composed of values derived from natural capital and ecosystem services. It models households, producing sectors, and governments, linked to one another through commodity and factor markets. GEMES was designed to model the typical resource-dependent economy, and so it has several innovations not found in other general equilibrium models; for example, ecosystem services and natural capital are explicitly modeled, allowing for endogenous nonmarket values. Households gain utility from nonconsumptive use of natural resources, and the value of those resources depends on both the state of the resource and the costs of turning that resource into an enjoyable experience. We allow for environmental regulations such as quotas on harvest and taxes on environmental goods.