Elastic incoherent neutron scattering is employed to parameterize changes in the atomic/molecular mobility in lithographic polymers as a function of film thickness. Changes in the 200 MHz and faster dynamics are estimated in terms of a harmonic oscillator model and the corresponding Debye–Waller factor mean-square atomic displacement 2>. We generally observe that relatively large 2> values in the glassy state lead to a strong suppression of 2> when the polymer is confined to exceedingly thin films. In contrast, this thin film suppression is diminished or even absent if 2> in the glass is relatively small. We further demonstrate that highly localized side group or segmental dynamics of hydrogen-rich moieties, such as methyl groups, dominate 2> and that thin film confinement apparently retards these motions. With respect to photolithography, we demonstrate that a reduced 2> in exceedingly thin model resist films corresponds to a decrease in the reaction front propagation kinetics. © 2003 American Institute of Physics.