Adsorption isotherms of alkylbenzene-derived amphiphiles were determined experimentally and correlated with their activity as stabilizers of asphaltenes. The isotherms of these amphiphiles indicate an adsorption process in two steps: in the first step, the amphiphiles are adsorbed through the interactions with the surface of the asphaltene particles; in the second step, the interactions between adsorbed amphiphiles become predominant and the formation of aggregates on the surface begins. A direct correlation was also found between the maximum surface excess concentration of the amphiphile and its activity as stabilizer. This indicates that the aggregation of amphiphiles on the asphaltene surface plays a very important role in the inhibition of the precipitation of asphaltenes.