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New low-resolution UV spectra of a sample of reddened OB stars in M31 wereobtained with HST/STIS to study the wavelength dependence of interstellarextinction and the nature of the underlying dust grain populations. Extinctioncurves were constructed for four reddened sightlines in M31 paired with closelymatching stellar atmosphere models. The new curves have a much higher S/N thanprevious studies. Direct measurements of N(H I) were made using the Ly$\alpha$absorption lines enabling gas-to-dust ratios to be calculated. The sightlineshave a range in galactocentric distance of 5 to 14 kpc and represent dust fromregions of different metallicities and gas-to-dust ratios. The metallicitiessampled range from Solar to 1.5 Solar. The measured curves show similarity tothose seen in the Milky Way and the Large Magellanic Cloud. The Maximum EntropyMethod was used to investigate the dust composition and size distribution forthe sightlines observed in this program finding that the extinction curves canbe produced with the available carbon and silicon abundances if the metallicityis super-Solar.

New Ultraviolet Extinction Curves for Interstellar Dust in M31