A branched polycarboxylic acid or salt thereof, wherein the average number of branches is (2) to (100) and the average degree of polymerization of the branches is (2) to (50), is an effective polymeric dispersant. More specifically, the polymeric dispersant is a branched polycarboxylic acid or salt thereof, in which the branched polycarboxylic acid is derived from polymerization of (meth)acrylic acid; the average degree of polymerization is (10) to (150); the average number of branches is (2) to (20); and the average degree of polymerization of the branches is (2) to (30). The branched polycarboxylic acid or salt thereof can be combined with a pigment to form an aqueous dispersion. An aqueous coating composition includes the aqueous dispersion; a polymeric binder; and a rheology modifier.