Corporate centers vary radically in size and activity. Companies with 10,000 employees, for example, may have as few as 20 people in their headquarters or as many as 4,000. (See “When Lean Isn’t Mean,” HBR Forethought, April 2005.) Given this diversity, how can companies decide what size and composition of corporate staff is right for them? And what role, if any, should benchmarking play in these decisions?