Expressions for calculating the stationary state distribution of radicals in a bidisperse seed system initiated by oil-soluble initiators were developed. Dimensionless parameters were used throughout, thus making it possible to obtain general trends without introducing specific numerical values. Desorption and reabsorption of radicals, aqueous phase termination, partition of the initiator into the aqueous phase, and a possible generation of single radicals are taken into account. The radical entry and exit rate coefficients are formulated in terms of power laws with respect to particle diameter. No discrimination of the various radical species and their origin is made. The derivation is based on a probabilistic stationary state analysis leading to third-order recurrence relations that are solved using confluent, hypergeometric Kummer functions. A selection of curves illustrating the effect of various dimensionless parameters on the calculated average number of radicals per particle, the order of volume growth with respect to the particle diameter, and relative rates are given.