This article explores the impacts of oil palm expansion on biodiversity and tropical deforestation. Oil palm plantations support substantially less biodiversity than natural forest or even other tree crops. Because regions with favorable conditions for oil palm plantations tend to be areas of critical importance for biodiversity, the rising international demand for vegetable oils and biofuels could prompt further wide-scale tropical deforestation and large losses of biodiversity unless there are interventions to prevent deforestation in future palm oil expansion