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We present a brief review of molecules studied with far‐ultraviolet spectroscopy, discussing absorption line measurements of the dominant interstellar molecules (H2 and CO) and H2 emission from molecular clouds near hot stars. We give two examples where the CO/H2 ratio, which can only be derived uniquely in the far‐ultraviolet, can be used to study the structure of the interstellar medium. Prospects are discussed for future work with deeper observations that would allow one to probe farther into molecular clouds in the galaxy. We describe a mini‐survey of five local photodissociation regions (PDRs) carried out with FUSE. We use these data to characterize the far‐UV spectra of PDRs for the first time and to refine models of the H2 fluorescent emission process. We find that our models can adequately reproduce the observed emission spectra of three of these regions (IC 63, M42, and IC 405). The remaining two (NGC 2023 and NGC 7023) do not show clear emission from H2 in the FUSE band, despite the well defined...