Macroporous poly(dicyclopentadiene) beads have been produced via chemically induced phase separation in suspension polymerization. Phase separation is promoted by the enthalpic and entropic changes induced by the polymerization of dicyclopentadiene. By using poly(1,2-butylene glycol) monobutyl ether (M n 500 g/mol), which is not soluble in the suspending medium, as the porogen, the stabilized droplets of the monomer/porogen mixture can be considered microreactors in which both polymerization and phase separation occur, resulting in solid, biphasic microspheres. The porogen is then extracted with methanol and the particles are finally dried. The resulting macroporous crosslinked poly(dicyclopentadiene) beads are analyzed by scanning electron microscopy, mercury intrusion porosimetry, and nitrogen adsorption and are compared with similar bulk samples. Materials containing isolated pores as well as microstructures built with agglomerated particles have been produced. The porous microspheres showed micrometric average pores' access diameters and specific surface areas ranging from 1.3 to 3.1 m 2 /g.