Direct marketing has been a staple of many companies marketing mix for decades, and many successful companies have been built with direct marketing as the backbone of their marketing initiatives. Like any marketing expense, it is important to understand the return that you are making with such an investment. Ideally, you want to be generating a return on investment that exceeds the performance you could achieve by using those expense dollars in other areas of the company or investing them. To measure ROI, you need to carefully track your costs, response and conversion rates and sales so that you know which sales can be tracked back to a particular campaign.