Luther Gulick was an American expert on public administration who developed theories on management and organization. He formulated the POSDCORB principles which outline the main functions of management as Planning, Organizing, Staffing, Directing, Coordinating, Reporting and Budgeting. Gulick also developed the concepts of departmentalization and the unity of command principle. While influential, Gulick's theories were criticized for being oversimplified and vague in application to real organizations. His POSDCORB principles in particular were criticized for potential contradictions and ambiguities.