PIP: Concern is rising over the deleterious effects of tropical deforestation. For example, the loss of forest cover influences the climate and reduces biodiversity, while reduced timber supplies, siltation, flooding, and soil degradation affect economic activity and threaten the livelihoods and cultural integrity of forest-dependent people. Such concerns have led economists to expand their efforts to model why, where, and to what extent forests are being converted to other land uses. This synthesis of the results of more than 140 economic models analyzing the causes of tropical deforestation brings into question many conventional hypotheses upon deforestation. More roads, higher agricultural prices, lower wages, and a shortage of off-farm employment generally lead to more deforestation. However, it is not known how technical change, agricultural input prices, household income levels, and tenure security affect deforestation. The role of macroeconomic factors such as population growth, poverty reduction, national income, economic growth, and foreign debt is also unclear. The authors nonetheless determine through their review that policy reforms included in current economic liberalization and adjustment efforts may increase pressure upon forests.