Nucleation transients are important features in the reactive generation of monodisperse colloids from solutin. Many previous theoretical investigations, both analytical and numerical, have addressed the roles of coloid aggregation or of direct growth from solution. Few have addressed the role of nucleation transients on the size distribution. The population balance model was used to study the effect of nucleation transients on an aggregating colloidal dispersion. (To simplify the problem, growth was neglected.) The focus was on whether, under the action of aggregation alone, extended and divided nucleation periods in some cases can lead to a very narrow particle-size distribution. Our results support previous treatments (Look et al., 1990; Bogush and Zukoski, 1991b) suggesting this is the case. Our general approach also offers additional insights, such as strategies to manipulate the nucleation transients to independently tune the average particle size and the variance of the distribution.