Block copolymers (BCPs) offer an exciting range of structures and functions that are of potential utility in existing as well as emerging technologies. Although this is generally acknowledged, with few exceptions, viable strategies for establishing scalable and robust control of BCP microstructure are underdeveloped. Magnetic field alignment offers great potential in this regard. The physics bears much in common with electric field alignment, but the absence of dielectric breakdown concerns and the more flexible, space pervasive nature of magnetic fields make it possible to design processes for high-throughput fabrication of well-ordered films with appropriate materials. In this perspective, we highlight the use of magnetic fields for control of microstructure in BCPs as well as polymer nanocomposites involving anisotropic nanomaterials. A brief review of efforts to date is given. Open questions related to field-polymer interactions and future directions for magnetic alignment of these systems are discussed. (C) 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011