Pastoral managers face a bewildering array of management options while striving to remain viable. Many researchers and extension officers are forced to specialise, and "do good science" at the expense of working within a broader picture of practical station management. As a result their information and advice is often directed towards only part of a property's total management system. The development of new advisory tools, many of them using micro-computers, offer government officers and pastoral managers alike greater opportunities for effective interaction. We present the philosophy and structure of one tool, which has evolved with these developments, RANGEPACK HerdEcon, a dynamic herd or flock model linked to property cash flows. It can operate at a simple level initially, but it is able to mimic complex situations just as easily. Designed to accommodate sheep, cattle or mixed enterprises, it will enable a pastoral manager or an extension officer to develop management strategies for a particular property, which deal effectively with climatic variation, resultant animal production and subsequent cash flows. RANGEPACK HerdEcon will run on IBM compatible personal computers with at least 512k of RAM.