  We derive the mean wavelength dependence of stellar attenuation in a sample
of 239 high redshift (1.90 < z < 2.35) galaxies selected via Hubble Space
Telescope (HST) WFC3 IR grism observations of their rest-frame optical emission
lines. Our analysis indicates that the average reddening law follows a form
similar to that derived by Calzetti et al. for local starburst galaxies.
However, over the mass range 7.2 < log M/Msolar < 10.2, the slope of the
attenuation law in the UV is shallower than that seen locally, and the UV slope
steepens as the mass increases. These trends are in qualitative agreement with
Kriek & Conroy, who found that the wavelength dependence of attenuation varies
with galaxy spectral type. However, we find no evidence of an extinction "bump"
at 2175 A in any of the three stellar mass bins, or in the sample as a whole.
We quantify the relation between the attenuation curve and stellar mass and
discuss its implications.
