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, its important to understand the return that you're making on such an investment. Ideally, you want to be generating a return on investment that exceeds the return you could achieve by using those expense dollars in other areas of the company or investing them. To effectively 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 specific campaign.