Dispersing agents especially useful as cement plasticizers are copolymers obtained by polymerizing a) 5 to 70 percent by weight of ethylenically unsaturated monocarboxylic acids, carboxylic acid amides, dicarboxylic acids, or their anhydrides and/or (meth)acrylic acid monoesters of dialcohols, b) 1 to 40 percent ethylenically unsaturated, sulfonate-functional or sulfate-functional compounds, c) 10-80 percent of ethylenically unsaturated compounds of polyethylene glycols containing 1 to 300 ethylene oxide units, and terminal OH groups or —OR′ ether groups, d) 5 to 80 percent of ethylenically unsaturated compounds of polyalkylene glycol containing 1 to 300 C3-4 alkylene oxide units and terminal OH groups or —OR′ ether groups, the percentages totaling 100 percent by weight.