Alkali-soluble resins (ASRs) are widely used as electrosteric stabilizers as they incorporate advantages in the end-use properties of the waterborne dispersed polymers. The kinetics of the miniemulsion polymerization stabilized with ASRs was studied under industrial-like conditions, using redox initiator systems yielding widely different radicals. It was found that the hairy layer of alkali-soluble resin around the polymer particle reduced the entry rate of hydrophobic radicals formed in the aqueous phase, presumably due to diffusional limitations and/or to the formation of nonreactive tertiary radicals in the ASR backbone by hydrogen abstraction. The entry of anionic radicals formed in the aqueous phase was additionally hindered by the electrostatic repulsion, drastically reducing the efficiency of these radicals to initiate the polymerization.