Prior to joining the Department of Education, Miller had been an operating partner since 2007 with Silver Lake Partners, an investment firm. From 2003 to 2006, Miller was executive vice president of operations at LRN Corporation, a provider of governance and compliance software and legal research services. He also worked for 10 years at McKinsey & Company, where he was a partner that specialized in growth strategies, operating performance improvement, and restructuring for companies throughout the United States, Europe, and Asia.[dead link]
From 1984 to 1990, Miller also worked for Delco Electronics, a subsidiary of GM Hughes Electronics, where he managed regional channel marketing.