Precision Measurement of the Neutron A1n at JLab 11 GeV

I will first provide a brief review on our current understanding of the nucleon spin, then focus on the nucleon spin structure in the deep-valence quark (high x) region. I will report on a 12 GeV Jefferson Lab experiment (E12-06-110) that measured the virtual photon asymmetry of the neutron, A1n, using a 10.384 longitudinally polarized electron beam and a polarized 3He target. Preliminary results on A1(3He), A1n, and the quark polarizations will be presented.