Abstract: Thermosetting coating compositions, e.g., powder coating compositions, are provided and comprise: (a) a first reactant having functional groups, e.g., an epoxide functional (meth)acrylic polymer; (b) a second reactant having functional groups that are co-reactive with the functional groups of the first reactant, e.g., a carboxylic acid functional crosslinking agent; and (c) a polymeric flow control agent. The flow control agent is a block copolymer prepared by controlled radical polymerization and comprises: (i) a first block containing residues of at least one first ethylenically unsaturated radically polymerizable monomer that is free of hydroxy functionality; and (ii) a second block containing residues of at least one second ethylenically unsaturated radically polymerizable monomer that is free of hydroxy functionality. The second monomer of the flow control agent has a calculated Tg of at least 20° C. greater than that of the first monomer.