A structural characterization of the multicomponent system poly(oxyethylene) surfactant/water/ethanol/vinyl acetate has been attempted, using the spin probe technique, Four spin probes with various polarities have been used to probe the formation of surfactant aggregates, as well as their structural characteristics (local polarity, microviscosity, and order of the surfactant chains) vs composition for a series of monophasic samples with a constant ethanol/vinyl acetate ratio, The composition ranges where aggregation occurs are shown. It has been shown that, while vinyl acetate is solubilized in the poly(oxythylene) region of the aggregates, ethanol does not seem to be involved in the aggregate construction.