Combining SEGUE-1 and 2 revealed the complex kinematic and chemical substructure of the galactic halo and disks, providing essential clues to the assembly and enrichment history of the galaxy. In particular, the outer halo was expected to be dominated by late-time accretion events. SEGUE data can help constrain existing models for the formation of the stellar halo and inform the next generation of high resolution simulations of galaxy formation. In addition, SEGUE-1 and SEGUE-2 may help uncover rare, chemically primitive stars that are fossils of the earliest generations of cosmic star formation.