We report the discovery of a circumstellar debris disk viewed nearly edge-on and associated with the young, K1 star BD 45 degrees 598 using high-contrast imaging at 2.2 mu m obtained at the W.M. Keck Observatory. We detect the disk in scattered light with a peak significance of similar to 5 sigma over three epochs, and our best-fit model of the disk is an almost edge-on similar to 70 au ring, with inclination angle similar to 87 degrees. Using the NOEMA interferometer at the Plateau de Bure Observatory operating at 1.3 mm, we find resolved continuum emission aligned with the ring structure seen in the 2.2 mu m images. We estimate a fractional infrared luminosity of L-IR/L-tot similar or equal to 6(-1)( 2) x 10(-4), higher than that of the debris disk around AU Mic. Several characteristics of BD 45 degrees 598, such as its galactic space motion, placement in a color-magnitude diagram, and strong presence of lithium, are all consistent with its membership in the beta Pictoris Moving Group with an age of 23 /- 3 Myr. However, the galactic position for BD 45 degrees 598 is slightly discrepant from previously known members of the beta Pictoris Moving Group, possibly indicating an extension of members of this moving group to distances of at least 70 pc. BD 45 degrees 598 appears to be an example from a population of young circumstellar debris systems associated with newly identified members of young moving groups that can be imaged in scattered light, key objects for mapping out the early evolution of planetary systems from similar to 10-100 Myr. This target will also be ideal for northern-hemisphere, high-contrast imaging platforms to search for self-luminous, planetary mass companions residing in this system.
