An aqueous composition comprising at least 18% surfactant and colloidal inorganic clay. This composition is stable with regard to phase separation at 40.degree. C. for at least three months and exhibits increased low-shear viscosity relative to a composition without clay. The composition comprises at least one lipophilically-modified copolymer containing acrylic acid residues and C.sub.2 C.sub.4 alkyl (meth)acrylate residues.