The need for long-term agricultural research is generally recognized. However, most long-term experiments have been designed to evaluate effects of fertility and crop rotation. Much of the current research in weed biology and weed management is conducted on a short-term basis that does not address adequately the long-term aspects of weed population ecology. In recent decades, a number of long-term experiments have been initiated to investigate the effects of both agronomic and weed management practices on weed communities. Knowledge of the existence of these experiments and the information being obtained from them are not always readily available. The Symposium held at the 2002 WSSA annual meeting in Reno, Nevada, had several goals: (1) to provide WSSA members, and other researchers, with information about long-term experiments that are currently ongoing, or recently terminated, that are investigating weed ecology and weed management; (2) to provide an exchange of ideas between researchers involved in long-term weed ecology research; (3) to provide examples of protocols and problems associated with conducting long-term weed ecology research; (4) to evaluate the scientific principles that have been, or may be, added to the discipline of weed science; and (5) to provide funding agencies with examples of how long-term weed management experiments clarify impacts of weeds in relation to sustainable agriculture.