The　thermodynamics　of　the　micellization　of　long-tail　surfactants,　including　docosyl-,　eicosyl-,　and　octodecyl-trimethylammobium　bromide　(C(22)TABr,　C(20)TABr,　and　C(18)TABr),　docosylethoxyldimethyl-ammonium　bromide　(C-22(OH)DABr),　and　docosylbenzyldimethyl-ammobium　bromide　(C(22)BzDABr),　have　been　studied　using　static　light　scattering　measurements　in　ethanol　following　addition　of　water.　The　water　content　was　found　to　influence　the　thermodynamics　of　micellization.　In　this　study,　the　surfactants　examined　were　at　mmol　center　dot　L-1　concentrations　in　ethanol　and　thereby　the　critical　water　content　inducing　aggregation　was　always　smaller　than　50　wt%.　All　the　thermodynamic　functions　are　negative　over　the　concentration　range　investigated.　The　micellization　is　mainly　enthalpy-　and　partly　entropy-driven.　With　continuously　increasing　water　content,　the　entropic　contribution　to　the　driving　force　increases.　The　critical　water　contents　leading　to　the　transition　from　mainly　enthalpy-driven　to　mainly　entropy-driven　behavior　are　66.9　wt%　(C(22)BzDABr),　73.2　wt%　(C(22)TABr),　and　77.1　wt%　(C-22(OH)DABr),　respectively.　Enthalpy-entropy　compensation　occurs　during　the　micellization　processes.　The　compensation　temperatures　T　(c)　are　close　to　the　general　values　for　surfactants　in　aqueous　solution.