The Fermilab E-906/SeaQuest experiment is part of a series of fixed target Drell-Yan experiments designed to measure the antiquark structure of the nucleon and the modifications to that structure when the nucleon is embedded in a nucleus. Its principal goal is to extend the landmark measurement of the sea flavor asymmetry d̄ (x)i ū (x) in the proton made by its predecessor, E866, to the high-x regime. SeaQuest provides unique access to the vanishing sea quark density at high x via the luminosity and beam energy of the Fermilab Main Injector and the innate sensitivity of the Drell-Yan process to antiquarks. The experiment will also measure Drell–Yan from nuclear targets, to address the puzzle of the as-yet unobserved EMC effect in Drell–Yan and to learn more about parton energy loss in cold nuclear matter. See attached pdf for full description.