Disclosed is a highly effective detergency builder system comprising the combination of a particular ether carboxylate sequestering agent and particular types of dispersing/anti-redeposition agent. Such a selected ether carboxylate is oxydisuccinic acid or oxydisuccinate. Such particular dis- peraing/anti-redeposition agents can include salts of acrylic acid-based polymers and co-polymers or can include certain ethoxylated amine materials. This selected combination of a particular ether carboxylate sequestering agent and particular dispersing/anti-redeposition agents provide an especially useful builder system for use in phosphorus-free detergent or laundry additive products.