The dynamic surface tension behavior of a nonionic surfactant that incorporates the light-sensitive azobenzene group into its tail is investigated and reported. Cis-trans photo-isomerization of this group alters the aggregation state of the surfactant in bulk solution and changes its adsorption capacity at an air-water interface. NMR studies indicate that a solution removed from light for an extended period of time is comprised almost entirely of the trans isomer, while samples exposed to light of fixed wavelength eventually reach a photostationary state containing significant amounts of both isomers. Dynamic surface tension studies performed on this system under different illumination conditions (dark, visible light, UV) show profoundly different approaches to equilibrium. Above the CMC, the same equilibrium tension is reached in all three cases, presumably corresponding to a surface saturated with the trans (more surface active) isomer. The dark sample shows a single tension relaxation after creation of a fresh interface, while mixtures containing cis surfactant exhibit a more rapid initial decrease in tension, followed by a plateau of nearly constant tension, and end with a second relaxation to equilibrium. This behavior suggests competitive adsorption between the cis and trans isomers present in the mixtures. Diffusion models were developed to estimate the time scales expected for the surface tension relaxations seen in the dynamic measurements. These models account for the presence of aggregates in solution, and in the case of the dark samples, good agreement is found between the experimentally observed relaxation times and the model predictions.