The dynamic surface tension behavior of a nonionic photoresponsive 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 also changes the adsorption capacity of the surfactant 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.  UV-Vis absorption experiments have established that conversion between photostationary states is reversible, and is rapid under high-intensity illumination.  Dynamic surface tension studies performed on this system under different illumination conditions (dark, UV light, visible light) show profoundly different approaches to equilibrium.  At concentrations well 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 relaxation in surface tension 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 seems to suggest competitive adsorption occurring between the cis and trans isomers present in the mixtures such that the cis isomer reaches the interface more quickly and dominates the surface, causing the plateau of nearly constant tension, before ultimately being displaced by the trans isomer.  This hypothesis is supported by surface pressure measurements of adsorbed monolayers of the surfactant under various illumination conditions made using a Langmuir film balance.  In other experiments, a pendant bubble of air was formed inside a cuvette containing surfactant solution and allowed to reach a final trans-saturated equilibrium state (as determined from the surface tension) before being illuminated with a high-intensity UV light source.  The surface tension then rapidly increased to a higher, cis-dominated value and remained at this value for as long as the illumination persisted.  Upon discontinuing the UV illumination, the surface tension eventually returned to the lower, trans-dominated value, further evidence supporting the competitive adsorption and displacement theory. Diffusion models were developed to estimate the time scales expected for the surface tension relaxations seen in the dynamic surface tension measurements. These models account for the presence of aggregates in solution, and good agreement is found between the experimentally observed relaxation times and the model predictions, though the precise role of aggregates in the adsorption process is unclear.