This invention provides an effect pigment-containing, water-borne base coating composition comprising water-dispersible acrylic polymer particles (A) and effect pigment (B), the water-dispersible acrylic polymer particles (A) being obtained by emulsion polymerization of a radical-polymerizable unsaturated monomeric mixture including an amido-containing, radical-polymerizable unsaturated monomer having at least two radical-polymerizable unsaturated groups per molecule, and the effect pigment (B) being contained at a pigment weight concentration (PWC) within a range of 15-50%.