There is a growing trend in business to develop systems using rapid development tools and methods rather than using traditional systems analysis and specification methods. Some writers have warned of a return to the early "fag-packet" style of systems development. This paper uses the discipline of requirements engineering to validate the use of RAD techniques in identifying and responding to users' requirements for new systems. It argues that traditional systems analysis depended on identifying explicit requirements that could be verbalised; many new information systems, however, depend on identifying different forms of knowledge and requirements. Techniques employed by RAD and DSDM are eminently suited to eliciting these requirements.