After graduating in 1954, Daniel served as an officer of the
U.S. Navy Supply corps, where he worked with early IBM mainframes. He joined
McKinsey & Company, Inc. in 1957 and was a senior partner from 1968 to 1990. He served as managing director for twelve years (1976-1988) preceding
Fred Gluck, and was senior partner emeritus of the firm. At McKinsey, Daniel developed the concept of "success factors", which led to the emergence of
critical success factors, those "areas of [business] activity that should receive constant and careful attention from management". He hired and mentored future managing director
Rajat Gupta. He was
Jeffrey Skilling's former boss before Skilling became CEO of
Enron. In 2004, he described himself as "the bridge between McKinsey's founding generation and the present". Outside McKinsey, he was a director of
Yum! Brands and chairman of New York-based private equity firm
Ripplewood Holdings. ==Public service career==