Block copolymers have garnered significant attention in the past few decades due to their ability to self-assemble into nanoscale structures (similar to 10-100 nm), making them ideal for emerging nanotechnologies, such as nanolithography, nanotemplating, nanoporous membranes, and ultrahigh-density storage media. Many of these applications require thin film geometries, in which the block copolymers form well-ordered nanostructures and/or precisely controlled domain orientations. In this Perspective, we discuss recent progress toward techniques that achieve directed self-assembly of block copolymer thin films. Substrate prepatterning, nanoimprint lithography, molecular transfer printing, solvent treatment, and zone processing approaches are highlighted. Finally, we comment on recent developments in high-throughput and in situ characterization methods, and we provide future research directions for thin film nanostructure refinement.