Crittenden began his career as a consultant at Bain and Company where he worked on various strategic projects in the United States and Germany. Crittenden served as CFO and executive Vice President at Melville Corp. While at Melville, he was the architect of the breakup of the company that led a significant increase in share price as the company was split into three firms. He was the CFO of Sears Roebuck and Company from 1997 to 1998. He then served as the CFO of Monsanto Company from 1998 to 2000. At Monsanto, Crittenden led the efforts to acquire seed companies DeKalb Genetics Corporation, and the Delta and Pine Land Company. He also played a key role in the eventual sale of Monsanto to Pharmacia & Upjohn. Prior to joining Citigroup, Crittenden was Executive Vice President and Chief Financial Officer (CFO) of American Express, as well as the head of the company's Global Network Services division.