[Presented at HWO25 "Towards the Habitable Worlds Observatory: Visionary Science and Transformational Technology"] A primary goal of the Habitable Worlds Observatory (HWO) is to detect and measure the abundance of biosignature molecules, such as water (H2O) and oxygen (O2), in the atmosphere of Earth analogs. Moderate to high-resolution spectroscopy (R>1000) can resolve the distinct spectral features of chemical species in exoplanet atmospheres. It is a powerful way to disentangle the planet signal from the stellar halo (i.e., speckles). In order to inform the optimal spectral resolution of the high-contrast spectrograph, we simulated observations of Earth analogs around 164 stars using representative mission parameters and post processing assumptions. Our findings suggest that a moderate or high resolution spectrograph (R>1,000) could be optimal to detect biosignatures. As a recent demonstration of this technique in space with JWST/NIRSpec (R~2,700), I will present the first detection of refractory species (sulfur; H2S) and isotopologues (13CO and C18O) in the HR 8799 multi-planet system as well as CO2, CH4, H2O, and CO.