Poly[styrene-co-(2-hydroxyethyl methacrylate)] core and shell latex particles easily undergo self-ordering, as evidenced by the iridescence of dispersions and dry solids. Microscopic (scanning electron microscopy) observation of the dry latex and fracture surfaces reveals the coexistence of different crystallographic arrangements. Many domains are observed, in which particle positions are correlated for tens of crystallographic planes. Isotherms of latex monolayers were also obtained, showing a strong interparticle repulsion. The ease of particle self-assembly in this latex is assigned to two factors: (i) the existence of strong repulsive interparticle interactions? which allows particle ordering at long distances, while particle diffusion throughout the dispersion is still possible: (ii) the hydrophilic surface layer, which allows for strong capillary adhesion during the whole drying process, according to Nagayama's model (Nature. 361 (1993) 26). (C) 1998 Elsevier Science B.V. All rights reserved.14441699207217