The critical micellar concentration (cmc) and energetics of surfactant self-organization have been reassessed at 303 K with the help of a high-sensitivity microcalorimeter. The calorimeter can operate in a stepwise addition mode, providing an excellent method of determination of cmc and enthalpy of demicellization (and hence micellization). It can as well distinguish between aggregating and nonaggregating amphiphiles (solutes) in solution. The reinvestigated surfactants are hexa-(cetyl-), tetra-, and dodecyltrimethylammonium bromide, cetylpyridinium chloride, sodium dodecyl sulfate, sodium bis(2-ethylhexyl)sulfosuccinate, sodium cholate, and polyoxyethylene tert-octyl ether.