The volatile abundances in Jupiter-family comet (JFC) 6P/d'Arrest were measured on two dates (UT 2008 July 28 and August 11) using high-dispersion (λ/Δλ ~ 2.8 × 10⁴) infrared spectroscopy with NIRSPEC at the W. M. Keck Observatory. H₂O, CH₃OH, and C₂H₆ were detected on both dates and H₂CO and NH₃ were detected on UT August 11. A tentative detection of HCN and an upper limit for C₂H₂ are also reported on UT August 11. CH₃OH, H₂CO, and NH₃ abundances relative to H₂O are in the typical range, while C₂H₆, C₂H₂, and HCN are all moderately to severely depleted compared to other comets. Gas production increased by about a factor of 2 from July 28 to August 11. Relative abundances of C₂H₆ and CH₃OH with respect to H₂O are consistent on these dates within the limitations of the measurements. Rotational temperatures were determined for H₂O on UT August 11 and found to be about 40 K. The spatial distributions of H₂O and C₂H₆ are both asymmetric with peak flux about 100 km in the anti-sunward direction compared to the more symmetric dust distribution. A comparison between the abundances of daughter fragments (e.g., C₂, CN, NH, and NH₂) and their suspected parents (e.g., C₂H₂, C₂H₆, HCN, and NH₃) shows that while the abundance of NH₃ in 6P is consistent with it being the primary source of NH and NH₂, there is insufficient C₂H₂, C₂H₆, and HCN to account for C₂ and CN in 6P. This is in contrast to other measured JFCs where abundances of C₂ and CN are consistent with C₂H₂, C₂H₆, and HCN as their primary parents to within the accuracy of the measurements. Thus, optical taxonomic classifications of comets may not correlate well to taxonomic classifications based on parent volatile chemistry in some cases.