An inverse emulsion thickener which imparts a short flow to a wide variety of aqueous and non-aqueous compositions and is effective over a pH range of 1-14. Supplied as an easy to use, low viscosity liquid which gives an instantaneous thickening effect on direct mixing into the composition. The polymer is already in solution (as the sodium salt) and requires no other additives to promote thickening e.g. alkali, surfactant etc.