We report on the development, calibration, and refinement of the SDSS-I Value Added Catalog (VAC) of stellar abundances, temperatures, and surface gravities. This catalog is based on observations of several hundred thousand stars obtained during the course of the original Sloan Digital Sky Survey, now known as SDSS-I. A spectroscopic pipeline has been developed that obtains estimates of [Fe/H], T[eff], and logg based on medium-resolution (R = 2000) spectra and ugriz photometry obtained with the ARC 2.5m telescope. This same pipeline is being used for estimation of stellar parameters for the ongoing SEGUE: Sloan Extension for Galactic Understanding and Evolution project. We discuss the methods explored for development of the VAC, as well as tests of the calibration based on high-resolution spectroscopy obtained with the Hobby-Eberly Telescope, the Keck telescopes, and the Subaru telescope