Laboratory investigations of the isomer-specific spectroscopy of several C₁₀H_n isomers with n = 8–12 are described, focusing on structures of relevance to the formation or subsequent reaction of naphthalene. The photochemical models of Titan's atmosphere have now progressed to the point that further development of the large-molecule end of the model must recognize and explicitly incorporate the unique spectroscopy, photochemistry, and reactivity of structural isomers. Mass-resolved, resonant two-photon ionization (R2PI) was used to record ultraviolet spectra of specific C₁₀H_n composition, while hole-burning methods were used to resolve the spectra of different structural and conformational isomers under jet-cooled conditions. The R2PI spectrum of a new C₁₀H₈ isomer, 1-phenyl-1-butyne-3-ene, is described and contrasted with other C₁₀H₈ isomers. The anticipated role for resonance-stabilized radicals is illustrated by studies of the visible spectroscopy of two hydronaphthyl radical isomers, 1-C₁₀H₉ and 2-C₁₀H₉, and the trihydronaphthyl radical 1,2,3-C₁₀H₁₁. Conformation-specific spectra of an anticipated C₁₀H₁₂ recombination product of benzyl and allyl radicals is also reported. A reaction scheme that fleshes out the experimental data surrounding naphthalene and its hydrogenated radicals and ions is proposed as a basis for future modeling under Titan's conditions.