A new index of relative deprivation is derived axiomatically. Thanks to an asymptotically concave individual contribution function, the new measure provides a sounder quantification to the concept of relative deprivation as conceptualized in the seminal work of Runciman (1966 ) and better reflects the sociological connotations of the phenomenon. Copyright 2010 The Author. Review of Income and Wealth 2010 International Association for Research in Income and Wealth.