To provide a silicone-modified aqueous dispersion in good polymerization stability with few coarse particles where the emulsion polymer and the silicone are in a homogeneous state, and to provide e.g. a water-based coating using the aqueous dispersion.

The aqueous dispersion is obtained by the following steps. (1) Emulsion copolymer particles are prepared by carrying out an emulsion copolymerization between 0.5-10 pt(s).wt. of a 3-8C unsaturated carboxylic acid compound, 10-99.5 pts.wt. of an acrylic 1-3C alkyl ester and 89.5-0 pt(s).wt. of an ethylenically unsaturated monomer, and (2) in the presence of the emulsion copolymer particles, an alkoxysilane compound is added at ≤30°C in the proportions described in (i) and (ii) below followed by temperature rise to 60-90°C to carry out a condensation reaction with the emulsion copolymer particle: (i) 4-30 wt. times the 3-8C unsaturated carboxylic acid compound, and (ii) 0.02-0.75 wt.% time the emulsion copolymer nonvolatiles. The water-based coating comprising the aqueous dispersion is also provided.