Photon correlation spectroscopy (PCS) has been employed to monitor the size evolution of aggregates of hematite particles in the presence of fairly monodisperse polyacrylic acid (PAA). The aggregation rate increases to a maximum value and then decreases as the PAA concentration is increased. This stability variation results mainly from a charge reversal of polymer coated particles, as revealed by electrophoretic mobility measurements. The maximum rate, occurring at low magnitudes of zeta potentials, is found to be identical to that induced by KCl above the critical coagulation concentration. Thus, it seems that polymer bridging is not important compared to the charge neutralization mechanism in the diffusion-limited aggregation (DLA) regime. Dynamic scaling yields the same fractal dimension for DLA aggregates induced by both PAA and KCl. This suggests that the polymer chains situated between contacting particles in an aggregate completely collapse on the surface so that the interparticle distance hardly increases in the presence of a flexible polyelectrolyte.