Online display advertising has become an accepted interactive marketing tool during the past 10 years, used by the majority of interactive marketers in Europe and the US. However, for many advertisers, the tools and techniques used to measure the success of display advertising are still evolving, both in terms of day-to-day success metrics and long-term evaluation of cross-channel impacts. Interactive marketers need to move away from success models based on basic reach or cost measures and implement more sophisticated technologies that allow for metrics driven more by campaign goals and on multiple-exposure attribution.