The constant challenge of managing uncertainty makes the professional development of school principals increasingly important. School improvement is unlikely to happen without qualified school leaders who continuously work on their professional development. This article explores professional development of school principals in Kazakhstan. Data were collected through document analysis and semi-structured interviews with thirty school principals from public and private schools. The outcome of the study indicates that professional preparation for school principals is crucial. School leaders do not have any induction courses prior to their service and often absorb everything as they get immersed by working out what needs to be done in process. Furthermore, current professional development programs do not meet the needs of school principals. The conclusion includes recommendations to improve professional development opportunities for school principals in Kazakhstan and a wider community.