ABSTRACTTo protect the elephant, trade in ivory has been banned since 1990. In this paper, we demonstrate that this ban's effect on elephant populations is ambiguous. Depending on the discount rate, among other things, the trade ban can either increase or decrease optimal population size. If the decision-maker's discount rate exceeds a certain threshold, the optimum stock of elephants is greater with a trade ban. Since the threshold is in the range of possible social discount rates, the success of the trade ban in promoting elephant conservation will vary spatially and temporally, depending on the characteristics and level of development of countries with significant elephant populations.