An apparatus for making in situ measurements of the magnetic moment of submonolayer through multimonolayer samples deposited in a UHV chamber is described. The UHV chamber is designed to be used with a commercial SQUID magnetometer with a sensitivity of approximately 10(-8) emu. The component of magnetic moment parallel to the sample surface may be measured over the temperature range 4-400 K and for magnetic fields (applied parallel to the surface) up to 5 T. A thin re-entrant metal tape is used both as an initial substrate for the deposition of any desired films, and as the means of transporting the deposited sample from the evaporation and evaluation regions of the vacuum chamber to the SQUID analysis region. Some results for Fe evaporated on polycrystalline Ag films are presented.