Robin Lake & Paul Hill, via a Deb Britt email:

Under pressure from state standards-based reform and No Child Left Behind, and with increasing competition from schools of choice, urban school districts are looking for ways to offer a high-performing mix of schools that meet the diverse needs of their communities.
Many districts see themselves as portfolio managers, operating some schools in the traditional way, hiring independent groups to run other schools, and holding all schools accountable under the same performance standards.
Portfolio management requires school districts to do three things they were not designed to do: judge the performance of individual schools, decide which are effective enough to continue supporting, and decide whether to shore up struggling schools or create new ones. Districts currently adopting a portfolio strategy, partially or fully, include New York, Chicago, New Orleans, Denver, Philadelphia, Hartford, and the District of Columbia. Many other districts are considering the strategy.
Performance Management in Portfolio School Districts provides ideas for portfolio school districts and others that are trying to manage schools for performance. Based on studies of other government agencies and businesses that have shifted from inputs- to performance-based accountability, this report:

Complete report: 1.3MB PDF.