  We present a new method for deriving UV-through-IR extinction curves, based
on the use of stellar atmosphere models to provide estimates of the intrinsic
(i.e., unreddened) stellar spectral energy distributions (SEDs), rather than
unreddened (or lightly reddened) standard stars. We show that this
``extinction-without-standards'' technique greatly increases the accuracy of
the derived extinction curves and allows realistic estimations of the
uncertainties. An additional benefit of the technique is that it simultaneously
determines the fundamental properties of the reddened stars themselves, making
the procedure valuable for both stellar and interstellar studies. We
demonstrate how the extinction-without-standards curves make it possible to: 1)
study the uniformity of extinction in localized spatial regions with
unprecedented precision; 2) determine the relationships between different
aspects of curve morphology; 3) produce high quality extinction curves from low
color excess sightlines; and 4) derive reliable extinction curves for mid-late
B stars, thereby increasing spatial coverage and allowing the study of
extinction in open clusters and associations dominated by such stars. The
application of this technique to the available database of UV-through-IR SEDs,
and to future observations, will provide valuable constraints on the nature of
interstellar grains and on the processes which modify them, and will enhance
our ability to remove the multi-wavelength effects of extinction from
astronomical energy distributions.
