The importance of effective school leadership is well known. The inevitable changing of school leaders raises concerns over the successfulness of the succession process. Directly linked to leader succession is socialization; therefore, the purpose of this study was to examine the processes and practices of school systems that control the organizational socialization of school principals as they succeed into the principalship. Using a multiple-case study approach, this qualitative inquiry examined the practices of four US school systems regarding the socialization of principals. The study, framed by organizational socialization theory, found a custodial response to socialization supported by collective, formal, serial, and investiture tactics. The implications of these findings are discussed in terms of what system leaders and policy-makers might consider in supporting the socialization process of new principals. (Contains 5 tables and 1 figure.)