Monodisperse PMMA-based terpolymer particles were synthesized by surfactant-free free radical emulsion polymerization. Particles with a wide and controllable range of size and polymer content were prepared by varying monomer amount, reaction temperature and initiator concentration. A kinetic study of the evolution of the terpolymer colloid composition and morphology reveals a mechanism of fast homogeneous nucleation. Copolymerization of the three monomers yields particles whose composition changes continuously during the reaction, which impacts polymer properties. Temperature and monomer amount are key parameters, particularly in the nucleation and growth stages of the reaction. A linear relationship between the particle size and reaction temperature is observed. This is attributed to the fact that the concentration of small, nucleated primary particles with high surface area, initiated at higher temperatures, is too large for efficient stabilization and hence they are more prone to aggregation. The linear relationship between the volume of the colloids and the ratio of main monomer to water in the reaction batch is due to the growth of the particles that continues while there is MMA available. The initiator concentration is not significant in terms of size and concentration of methacrylate-based colloids since primary particles are formed very early during polymerization and they are not dependent on the number of growing chains. The resulting “tailor-made” latexes are promising for a number of unique biotechnological and IC manufacturing applications.