Abstract: Dispersions are prepared by dispersing a polymer precursor such as a polyol into a non-aqueous fluid. The resulting droplets of the polymer precursor is partially polymerized to produce liquid or partially gelled droplets, and then sized to a target particle size. The sized particles are then cured to form solid particles. The process allows for close control of particle size, allows for good control of temperature, and is amenable to batch, semi-continuous or even continuous operation. The resulting dispersions are useful as electrorheological fluids.