A polyether polycarbonate block copolymer nonionic surface-active agent and method for making the same. The polyether polycarbonate surface active agent is comprised of a hydrophilic portion comprised of a polymer selected from the group consisting of a polyoxyalkylene polyether, a saccharide, a saccharide polyoxyalkylenate, a polycarbonate having a carbon dioxide content of from about 1 to 15 molar percent and mixtures thereof and a hydrophobic portion comprising alkylene and carbonate units arranged in alternating or random order to form a poly(alkylene carbonate) having a total carbon dioxide content of from about 25 to 50 molar percent and a total molecular weight of from about 300 to 10,000. The hydrophobic portion is bonded to the hydrophilic portion at each side of a reactive hydrogen. The surface active agent is prepared by polymerizing the hydrophilic portion with the hydrophobic portion in a weight ratio of about 10:90 to 90:10.