Foams are used to control and improve the injection profile in secondary or tertiary gas-injection processes and reduce gas mobility far from the injectors.  Over the last decade, significant progress has been made in the understanding of the complex foam processes in porous rock.  The goal of this paper is to review consistently, albeit somewhat subjectively, several important field tests of foams, compare their performance, and critically evaluate the economic benefits from foam injection.  It is shown that early, transient, and usually small oil production responses to surfactant injection are real, and depend critically on the reservoir architecture and gas flood implementation.  These early production responses are related to the improvements of gas-injection profile by foam and are often quite profitable.  The delayed, but bigger oil production responses are caused by foam propagation into the reservoir and could be very profitable, depending on the injection policy.  An outline of an ideal future foam pilot is presented, and important advances in rigorous modeling of foam processes are discussed.