Aggregation of some sulfur-containing compounds has been studied. The aggregators studied are p-nitrophenyl esters of butylsulfonate (S-4), octylsulfonate (S-8), dodecylsulfonate (S-12), and hexadecylsulfonate (S-16). Their aggregating tendencies have been evaluated By measuring their critical aggregate concentrations (CAgCs) in dioxane-H2O binary mixtures of graded compositions. Our results indicate that the sulfonates, just like the carboxylates or phosphonates, can also be used as kinetic probes for evaluating CAgC values. If the above-mentioned three types of compounds bearing the same number of methylene groups in their chains are compared, then the order of increasing aggregating tendency appears to be phosphonate < sulfonate and carboxylate.