The alignment of interstellar grains with the Galactic magnetic field has been known for nearly 50 years, but the physical process responsible for this alignment has proved elusive. A new mechanism -- radiative torques due to anisotropic starlight -- will be described and shown to play a critical role in dust grain dynamics.

For conditions appropriate to diffuse clouds, we expect slightly anisotropic starlight to be able to bring many dust grains into alignment with the local magnetic field on a ~10^6 yr timescale, about 10 times more rapidly than Davis-Greenstein alignment by paramagnetic dissipation. Radiative torques due to anisotropic starlight appear to be responsible for the observed alignment of dust grains with the Galactic magnetic field!