The possibility of obtaining narrowly dispersed particles through the controlled aggregation of polymer latices has been investigated. Concentrated polystyrene, poly(styrene-co-acrylic acid) and poly(styrene-co-butadiene-co-acrylic acid) latices were aggregated through the addition cationic surfactant under stirring. The method under investigation was proven to be effective in obtaining 5-15 mum particles with a narrow size distribution and a strong control of the average size. The aggregation properties of polymer latices were related to their chemical nature (chemical structure of the polymer and surface chemistry); the trends observed were explained through calculations of the fundamental forces involved in this process. Important differences were found between the aggregation of the latices that contain acrylic acid as a comonomer and those without acrylic acid. Narrow size distributions, with geometric standard deviations between 1.2-1.35 were obtained only for the latices containing acrylic acid. It was shown that on the surface of these particles there is a hairy layer formed by the polyacrylic acid chains. The thickness of this layer is dependent on the chemical environment and temperature. Its presence was demonstrated by capillary viscometry and electrophoretic mobility measurements.