An aqueous crosslinkable coating composition comprising an aqueous dispersion of: (A) at least one copolymer, said copolymer being obtainable or derived from the addition polymerization of 2 or more olefinically unsaturated monomers and bearing lateral carboxyl groups which are provided at least in part by polymerized units in said copolymer of a monomer of formula: CH.sub.2 .dbd.CR.sup.1 --Q--CO.sub.2 H, where R.sup.1 is H or lower alkyl of 1 to 5 carbon atoms and Q is a non carboxy-containing spacer group providing a spacer chain of a least 3 atoms, and (B) at least one carboxyl-reactive material for providing crosslinking during and/or after coating formation from the composition in which the polymer-bound carboxyl groups provided by the monomer of formula take part, and wherein the components (A) and (B) are provided by different and/or the same substance(s).