This document provides an overview of the theoretical foundations and general assumptions of the WVU Econometric Input-Output (ECIO) model. WVU Econometric Input-Output (ECIO) model (hereafter, ECIO model) is a time-series enabled hybrid econometric input-output (IO) model that combines the capabilities of econometric modeling with the strengths of IO modeling. It is designed to facilitate the estimation of economic (specifically, employment and income) impacts of energy technology development, deployment, and operation over a specified forecast period.