This article examines the feud between two management gurus – Bob Kaplan and Tom Johnson. Together, the two developed and introduced the world to Activity Based Accounting and later the Balanced Scorecard (Kaplan). While Kaplan still is preaching these concepts, Johnson has gone on to argue that the troubles that mainstream companies get into are due to the misuse of measurement. Thus, their quarrel, which has lasted more than 10 years, is at heart a fundamental disagreement about the source of business success. Does it accrue to those who drive their businesses with numerical targets and performance measures, as Professor Kaplan asserts? Or to those who believe, as Professor Johnson argues, that management through measurement is fundamentally dangerous?