The distribution of polymer terminal groups at surfaces and interfaces is assessed by neutron reflectometry (NR) experiments on end-functional polystyrenes. Mono-terminated polystyrenes (PS) are synthesized anionically to include a short perdeuteriostyrene sequence adjacent to the end groups for the purpose of selective contrast labeling of the end groups for NR. The location of deuterium serves as a marker to indicate the location of the adjacent end group. Three cases of end group surface segregation are examined: a «neutral» control specimen prepared by proton termination, a «repulsive» end group system terminated with high surface energy carborylic acid end groups, and an «attractive» end group system containing low surface energy fluorocarbon chain ends