The surface forces apparatus has been combined with fluorescence recovery after photobleaching to measure translational diffusion of polymer confined between mica sheets. This article presents findings using polydimethylsiloxane with number-average molecular weight M-n = 2200 g mol(-1), the chains end-labeled with soluble fluorescent dye. Melts with thickness 10 nm display a translational diffusion coefficient (D) with a bulk component and a slower component assigned to surface diffusion. Reduction of thickness to 1.8 nm causes mobility to split into two populations-an immobile fraction (immobile on the time scale of 30-60 min) and a mobile fraction who's D slow only weakly with diminishing film thickness. However, when load causes the confining mica sheets to flatten, D of the mobile fraction drops by up to an additional order of magnitude, depending on the local pressure that squeezes on the polymer. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 2582-2588, 2010