Half-mass Radii of Quiescent and Star-forming Galaxies Evolve Slowly from 0&xfffd;?&xfffd;z&xfffd;?&xfffd;2.5: Implications for Galaxy Assembly Histories** This work is based on observations taken by the CANDELS Multi-Cycle Treasury Program and the 3D-HST Treasury Program with the NASA/ESA HST, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. Journal Article