In the first part of this article, the surface characterization of multicomponent polymer systems is reviewed. The morphology, topography, and composition of copolymer and polymer blends in the top few 10s of angstroms of the surface depend strongly on the differences in the solid-state surface tensions of each component. In the second part, orientation control of microphase-separated structures is reviewed. The vertically or horizontally oriented microdomains of multicomponent polymer systems are fabricated by means of epitaxial growth or segment-segment interaction, respectively, of a domain on the surface of the substrate. Finally, miscibility behaviors of AB/BC type block copolymer blends are reported briefly.