Two American scholars won the 2009 Nobel Memorial Prize in Economic Science, the Royal Swedish Academy of Sciences announced this morning. One of the new laureates is the first woman ever to be awarded the Nobel in economics.

The prize, worth about $1.4-million this year, honors Elinor Ostrom, of Indiana University at Bloomington, and Oliver E. Williamson, of the University of California at Berkeley, for their work on theories of economic governance, an analytical approach dealing with many forms of social organization.

According to the academy, the two scholars, in work over the last three decades, have moved economic-governance research "from the fringe to the forefront of scientific attention."

Ms. Ostrom was cited for challenging the conventional notion that commonly held types of property -- such as fisheries, forests, and aquifers -- are so subject to conflicts of interest and other abuses by users that the only way to protect such property is to either privatize it or subject it to strict regulation by a central authority, on the national or international level. By contrast, she found that users of commonly held resources often make decisions and come up with enforceable rules that lead to better outcomes than the conventional wisdom would predict.

Mr. Williamson was cited for demonstrating that markets and business firms provide an alternative model for effective governance. "When market competition is limited," the academy said, "firms are better suited for conflict resolution than markets."

Ms. Ostrom and Mr. Williamson, who are both in their 70s, will receive equal shares of the award, formally the Bank of Sweden Prize in Economic Sciences in Memory of Alfred Nobel, at a ceremony in December. The award is the only one of the six Nobel Prizes not created in the will of the Swedish industrialist and first awarded in 1901. The prize was established by the Swedish bank in 1969.

The other 2009 Nobel Prizes were announced last week, in medicine, physics, chemistry, literature, and peace.