This invention relates to a process for preparing quinacridone pigment compositions by (a) heating a reaction mixture containing (i) 2,5-dianilinoterephthalic acid or 2,5-dianilino-6,13-dihydroterephthalic acid or a derivative thereof, (ii) about 0.1 to about 5 percent, based on component (a)(i), of 2,5-di(sulfamoylanilino)terephthalic acid and/or 2,5-di(sulfamoylanilino)-6,13-dihydroterephthalic acid or a derivative thereof, (iii) about 0.1 to about 15 percent by weight, based on component (a)(i), of other sulfonyl-containing derivatives of 2,5-dianilinoterephthalic acid and/or 2,5-dianilino-6,13-dihydroterephthalic acid, (iv) about 3 to about 20 parts by weight, per part of component (a)(i), of a dehydrating agent, and (v) optionally, a solvent; (b) drowning the reaction mixture from step (a) with a liquid in which the quinacridone pigment composition is substantially insoluble; and (c) isolating the quinacridone pigment composition.