A method for inhibiting scale comprises adding to a fluid that causes scale formation a polycarboxylic acid or a salt thereof which has a star structure and at least 5 arms. A star polymer comprising a core based on 2,2′-[Oxybis(methylene)]bis[2-(hydroxymethyl)-1,3-propanediol] and 6 arms comprising linear polycarboxylic acids of degree of polymerization (DP) of the arm of at least 2 and in some embodiments up to 15 or more is useful in inhibiting scale formation.