A process for printing an image on a substrate comprising the steps of: (a) applying an ink comprising polymer-encapsulated pigment particles and an aqueous medium to a substrate by means of an ink jet printer, wherein (i) the said particles are dispersed in the aqueous medium, and (ii) the said particles comprise a carboxy-functional dispersant crosslinked around a pigment core by a first crosslinking agent; and (b) crosslinking the polymer-encapsulated pigment particles with a second crosslinking agent. The process is particularly useful for printing polymeric substrates which come into contact with rubbing and/or moisture.