The purpose of the agro-ecological zone emission factor model (AEZ-EF) is to estimate the total CO2-equivalent emissions from land use changes, e.g., from an analysis of biofuels impacts or policy analyses such as estimating the effect of changes in agricultural productivity on emissions from land use. The model combines matrices of carbon fluxes (Mg CO2/ha/y) with matrices of changes in land use (ha) according to land-use category as projected by GTAP or similar AEZ-oriented models. As published, AEZ-EF aggregates the carbon flows to the same 19 regions and 18 AEZs used by GTAP-BIO, the version of GTAP currently used by Purdue University researchers for modeling biofuel-induced ("indirect") land-use change (ILUC) (e.g., Tyner, Taheripour et al. 2010). The AEZ-EF model, however, is designed to work with an arbitrary number of regions, as described in the accompanying report.