A handful of prominent charter school networks that have won praise for their academic performance and unorthodox models are expanding to new parts of the country, in some cases after receiving recruiting pitches from state and local officials determined to bring proven operators into their communities. Until now, organizations such as Aspire Public Schools and Rocketship Education, both with headquarters in California, and BASIS Schools Inc. of Arizona, which have been held up as worthy of emulation, have focused their work within their states' boundaries. But in recent months, those nonprofit organizations and others have announced plans for incremental growth, the success of which will determine whether they venture into other cities and states in the years to follow. The slow growth of those charter school operators underscores a sorting process in the charter school community. Some states and cities have resolved to be selective in choosing the organizations they allow to take over struggling schools or start new ones. Leaders of a number of highly regarded charter organizations, meanwhile, say they will only move to new locations that offer certain attributes--such as favorable financial conditions or a strong degree of independence.