For better or worse, most of us have at least one of the 720 million little plastic cards that are used each year to complete $860 billion worth of purchases at 15 million incredibly varied merchant locations throughout the world. This is a far cry from the humble beginnings of these myriad credit, debit, and charge cards, which just a few decades ago were generally a perk offered only to elite customers for the acquisition of fine meals, hotel rooms, department-store goods, and oil-company products. They are now so common and such an integral part of our economy, in fact, that few pay them much mind--a situation that makes David Evans and Richard Schmalensee"s Paying with Plastic all the more interesting. Evans, senior vice president of National Economics Research Associates, and Schmalensee, dean of MIT"s Sloan School of Management, meticulously trace the history of these cards from both the consumer and merchant perspectives in this surprisingly appealing volume, which will prove enlightening to anyone who ever wondered how plastic money works. --Howard Rothman