We present rest-frame optical spectroscopic observations of 24 Hot Dust-Obscured Galaxies (Hot DOGs) at redshifts 1.7-4.6 with KECK/NIRES. Our targets are selected, based on their extreme red colors, to be the highestluminosity sources from the WISE infrared survey. In 20 sources with well-detected emission, we fit the key [O III], Hβ, Hα, [N II], and [S II] diagnostic lines to constrain physical conditions. Of the 17 targets with a clear detection of the [O III]λ5007 Å emission line, 15 display broad blueshifted and asymmetric line profiles, with widths ranging from 1000 to 8000 km s −1 and blueshifts up to 3000 km s −1 . These kinematics provide strong evidence for the presence of massive ionized outflows of up to -M 8000 yr 1 , with a median of -M 150 yr 1 . As many as eight sources show optical emission line ratios consistent with vigorous star formation. Balmer-line star formation rates, uncorrected for reddening, range from 30 to 1300 -M yr 1 , with a median of -M 50 yr 1 . Estimates of the SFR from Spectral Energy Distribution fitting of mid-and far-infrared photometry suggest significantly higher values. We estimate the central black hole masses to be of order -M 10 8 10 , assuming the present-day s M BH *relation. The bolometric luminosities and the estimated masses of the central black holes of these galaxies suggest that many of the active galactic nucleus-dominated Hot DOGs are accreting at or above their Eddington limit. The combination of ongoing star formation, massive outflows, and high Eddington ratios suggest Hot DOGs are a transitional phase in galaxy evolution.Unified Astronomy Thesaurus concepts: Infrared galaxies (790); High-redshift galaxies (734); Active galaxies (17)