The presence of hydrophilic head groups in hydrophobic polymers has a dramatic effect on the ability of the polymer to spread into a smooth monolayer, as does the state of the polymer, i.e., melt or glassy. The influence of the glass transition on the surface activity of such polymers was measured by examining polybutylstyrene-N+ as a monolayer spread on a water surface at temperatures above and below its glass transition temperature and by investigating the behavior of the monolayer before and after vitrification.