Dynamic light scattering was used to study the particle formation in the dispersion polymerization of aniline hydrochloride. The organic polymers poly(N-vinylpyrrolidone) and hydroxypropylcellulose are compared with inorganic silica colloids in their role as steric stabilizers of polyaniline dispersions. The particle size, the relative width of the radii distribution of the particles, the intensity of scattered light, and the optical absorption have all been monitored during the polymerization. The aggregation of dispersion particles stabilized with hydroxypropylcellulose has been observed at the final stages of polymerization. The effect of temperature on the polymerization rate of aniline is reported in terms of activation energies.