The invention offers water-based paint compositions which comprise, as the polyester resin, a polyester resin whose constituent acid component contains no less than a specific amount of alicyclic polyvalent carboxylic acid (inclusive of anhydride of the acid) and which has an acid value and hydroxyl value each falling within a specific range; and as the high molecular weight resin, water-dispersible acrylic polymer particles having specific absorbance characteristics, i.e., having an absorbance not higher than a specific value as measured with a spectrophotometer in a state of a liquid dispersion at a specific low concentration in dioxane solvent, and also having a weight average molecular weight of at least 1,100,000; and multilayer coating film-forming methods using the water-based paint compositions.