User experience (UX) has gone mainstream: Companies now invest millions to build design centers and hire UX teams. But many firms still expect proof of the ROI of UX research, design, testing, and validation every step of the way — which customer experience (CX) professionals try but struggle to provide. This document outlines a six-step process that helps CX pros make that business case. This is an extensive update of a previously published report; Forrester reviews and updates it periodically for continued relevance and accuracy.