The present invention relates to a composition, especially a cosmetic composition, for caring for and/or making up keratin fibres, and more particularly the eyelashes, comprising at least: a non-aqueous medium containing at least one hydrocarbon-based oil, particles of at least one polymer surface-stabilized with a stabilizer, the polymer of the particles being a C1-C4 alkyl (meth)acrylate polymer the stabilizer being an isobornyl (meth)acrylate polymer chosen from isobornyl (meth)acrylate homopolymer and statistical copolymers of isobornyl (meth)acrylate and of C1-C4 alkyl (meth)acrylate present in an isobornyl (meth)acrylate/C1-C4 alkyl (meth)acrylate weight ratio of greater than 4 and a nonionic surfactant. The present invention also relates to a cosmetic process for making up and/or caring for keratin fibres, and also to the use of a dispersion of particles of at least one polymer surface-stabilized with a stabilizer in a non-aqueous medium containing at least one hydrocarbon-based oil, for preparing a mascara composition.
