a thickener composition for thickening aqueous compositions which contains a ) a water soluble or water dispersible thickener containing urethane groups , b ) a non - ionic aromatic or alkyl - substituted aromatic emulsifier and c ) a compound corresponding to formula i r . sub . 2 -- . sub . t h !. sub . u wherein r 2 represents an optionally branched and unsaturated aliphatic radical having 6 to 22 carbon atoms , a cycloaliphatic radical having 6 to 10 carbon atoms or a heterocyclic radical having 5 to 12 ring atoms , as obtained by removing the active hydrogen from a hydroxyl , amino , carboxylic acid or amide group , q 2 represents a c 2 - c 4 alkylene oxide unit , t has a value from 1 to 30 and u has a value from 1 to 10 , and d ) optionally further additives .