The article summarizes key insights from four laboratory experiments to study renewable resource management. The commons problem, which is widely held to be the cause of mismanagement of common renewable resources, was ruled out by the design of the experiments. Still the participants overinvested and overutilized their resources. The explanation offered is systematic misperceptions of stocks and flows and of nonlinearities. The heuristics that people apply are intendedly rational for static, flow resources, but not for dynamic, stock resources. Simplifying and reframing the management problem, by focusing on net growth rates, is suggested as a means to foster the use of more appropriate heuristics. Copyright © 2000 John Wiley & Sons, Ltd.