The initial droplet size distribution of mini-emulsions has not yet been measured. It is deduced from previous experimental results that the distribution is broad. Furthermore, the small fraction of the distribution, depending on the nonideality of the cosurfactant-monomer system, may not be stable. This may lead to a rearrangement of the distribution leading to a bimodal distribution. The stability criterion is based on the phenomenon of molecular diffusion or Ostwald ripening. Experimental proof in support of the conclusion regarding the bimodal distribution is cited. The practical significance of the conclusion for making emulsion polymers with high solid contents is given. (C) 2003 Wiley Periodicals, Inc.