Dark matter caustics are regions where the dark matter density is enhanced. In the self-similar model of halo formation, caustics of dark matter are expected to form at radii approximately 40/n kpc for n = 1,2,3... In recent years, observations by the SDSS and other surveys have revealed the existence of a ring of stars in the plane of the disk at about 20 kpc, commonly known as the Monoceros ring. In this talk, I discuss two processes by which the Monoceros ring could have formed due to the effect of a dark matter caustic at that location. The first is the migration of gas towards the caustic due to the effect of viscous torques. The other is the adiabatic deformation of star orbits as the caustic slowly grows in mass and radius.