The surface properties of a polydisperse poly(vinycaprolactam) (48 kDa) have been studied at the air/water and hexane/water interfaces. Adsorption of the polymer at both interfaces shows substantial time-dependent surface tension lowering at remarkably low concentrations in the aqueous phase. This adsorption is increased by addition of electrolyte, which also lowers the lower consolute temperature (LCT) of the polymer in solution. Adsorption is endothermic, corresponding with the approach to the LCT as the temperature is raised. Spreading of the polymer at the air/water interface from aqueous solutions is near quantitative. The surface pressure-area isotherms indicate extensive coiling in the monolayer at low pressures and looping of the polymer monolayer into the aqueous phase in the higher pressure range.