We present XMM-Newton observations of the radio galaxy 3C 120, which we use to study the nature and geometry of the X-ray and UV-emitting regions. Contemporaneous radio, mm-wave, and optical data provide additional constraints on the spectral energy distribution and physical state of the active galactic nucleus. The hard X-ray spectrum contains a marginally resolved Fe i Kα emission line with FWHM= 9, 000 ± 3, 000 km s −1 and an equivalent width of 57 ± 7 eV. The line arises via fluorescence in a broad-line region with covering fraction of 0.4. There is no evidence of relativistically broad Fe Kα, contrary to some previous reports. The normal equivalent widths of the X-ray and optical emission lines exclude a strongly beamed synchrotron component to the hard X-ray and optical continua. There is an excess of 0.3-2 keV soft Xray continuum over an extrapolation of the hard X-ray power-law, which may arise in a disk corona. Analysis of an archival Chandra image shows that extended emission from the jet and other sources contributes < 3% of the total X-ray flux. A break in the X-ray spectrum below 0.6 keV indicates an excess neutral hydrogen column density of N H = 1.57 ± 0.03 × 10 21 cm −2 . However, the neutral absorber must have an oxygen abundance of < 1/50 of the solar value to explain the absence of an intrinsic or intervening O i edge. There is no ionized absorption in the soft X-ray spectrum, but there is a weak, narrow O viii Lyα emission line. We do not detect previously claimed O viii absorption from the intervening intergalactic medium. Radio observations at 37 GHz show a fast, high frequency flare starting 7 days after the XMM-Newton observation. However, this has no obvious effect on the X-ray spectrum. The X-ray spectrum, including the soft excess, became harder as the X-ray flux decreased, with an estimated pivot energy of 40 keV. The UV and soft X-ray fluxes are strongly correlated over the 120 ks duration of the XMM-Newton observation. This is qualitatively consistent with Comptonization of UV photons by a hot corona.