Voluntary organizations providing inservice activities for principals are the newest in the administrative development field. This paper explores those organizations' prospects, particularly the voluntary, administrator-directed "principals' center," and borrows its analytical framework from theories of group formation. The Principals' Center in New Orleans, Louisiana evolved from an interest in Roland Barth's informal learning program for Boston principals. The Center brings in outside "major" speakers or workshop leaders twice yearly and organizes smaller programs during the year. Although the New Orleans structure used the Harvard Center as its model, it differs in the fund-raising area, relying on businesses, foundations, and school districts, whereas Harvard is funded by the Graduate School of Education. Harvard's initial planning was also determined by university personnel, as opposed to New Orleans' board of principals. As interest groups, principals' centers require financial bases and membership groups, both complex issues. Incentives to elicit contributions are important, as is proof of successful training of members. Unlike Harvard, New Orleans is weak in material and solidary incentives, and must basically rely on purposive incentives grounded in forward-reaching curricula and a philosophy of mutual support. (KS)