This report describes performance management by sourcing and vendor management leaders as part of Forrester's strategic software sourcing approach. Our conversations with clients and surveys with sourcing and vendor management professionals reveal widespread dissatisfaction with your most important vendors — the ones you call "strategic" and/or "partner." This report analyzes and explains some of the reasons for this unhappiness and suggests how to improve your key relationships by turning your suppliers into partners. It describes the key criteria for a good, successful strategic partnership and what to do about the powerful embedded vendors who don't want to embrace those criteria.