The tendency of block polymers containing two or more immiscible segments to undergo microphase separation and form periodic, compositionally pure domains on the nanometer length scale makes these types of materials attractive for a variety of applications. Through the judicious choice of the constituent chains, block polymers with desirable properties can be fabricated. In particular, this thesis will focus on using these types of materials a nanolithographic templates. We have employed two distinct strategies for the formation of nanoscale arrays: (1) incorporating etch-resistant segments directly into the block polymer, and (2) using external reagents that are resistant to etching as a mask for selected regions of the block polymer. The first half of this thesis will focus on the synthesis and use of block polymers containing both poly(lactide) (PLA) and poly(dimethylsiloxane) (PDMS) as nanolithographic templates. In these systems, the PDMS domains can be selectively oxidized to SiOx, which is highly resistant to subsequent etching steps. Through modulation of the block polymer composition and architecture, we will demonstrate the utility of these types of materials in the formation of nanoscale dot and ring arrays. The second half of this thesis will focus on using block polymers of poly(styrene) (PS) and PLA as well as PS, poly(isoprene) (PI) and PLA in conjunction with additional reagents as etch resistant masks. In these examples, the PLA domains are selectively removed, with the masking reagent residing in the resulting vacancies. These multi-component systems will be shown to be useful for the fabrication of nanoscale dot arrays.