This paper is focused on the influence of some amino acids or dipeptides (glycine, L-alanine, L-valine, L-threonine, L-proline, glycylglycine, and glycyl-DL-valine) and electrolytes (NaCl, MgCl(2), Na(2)SO(4), and Na(3)PO(4)) on the cloud point (CP) and surface properties of pure triblock copolymers [(EO)(2.5)(PO)(31)(EO)(2.5) and (EO)(13)(PO)(30)(EO)(13) (L-64)] and their mixed systems with cationic surfactants [dodecyltrimethylammonium bromide (DTAB), tetradecyltrimethylammonium bromide (TTAB), and hexadecyltrimethylammonium bromide] and anionic surfactants [sodium dodecylsulphate (SDS), sodium dodecylbenzene sulfonate (SOBS), and dioctyl sulphosuccinate sodium salt (AOT)]. The CP of the mixed system of triblock copolymers and surfactants is more than that of pure triblock copolymers. The decrease in the CP behavior of pure triblock copolymers as well as their mixed systems with ionic surfactants have been explained on the basis of the polar or nonpolar characteristics and the steric factor of the side chains of both amino acids and dipeptides. The variation of the CP of pure triblock copolymers and their mixed systems in the presence of electrolytes has been explained on the basis of salting-in or salting-out nature and the co- and counterion effect, respectively. The effect of amino acids or dipeptides on the surface properties of pure triblock copolymers and their mixed systems with ionic surfactants has been attributed to the hydrophobicity and steric effect of the side chains of these additives.