A phosphorus-free automatic dishwashing detergent composition comprising: (a) 0.5 to 10 wt % of a polymer comprising polymerized units of: (i) 65 to 75 wt % (meth)acrylic acid, (ii) 15 to 25 wt % of a monoethylenically unsaturated dicarboxylic acid and (iii) 7 to 13 wt % 2-acrylamido-2-methylpropanesulfonic acid (AMPS); and having Mw from 5,000 to 100,000; (b) 15 to 50 wt % carbonate, (c) 0 to 50 wt % citrate and (d) 10 to 40 wt % of a bleaching agent.