Water-swellable compositions, dispersions and hydrophilic cross-linked polymer microparticles for their preparation as well as their manufactures and uses are described. The polymer microparticles are formed from a monomer blend comprising sulphonic monomer, nonionic monomer and optionally other monomers and have a volume mean average size of below 20 microns. The compositions are useful in applications, such as seals and other water blocking applications.