Also see the archival list of Science's Compass: Enhanced Perspectives ECOLOGY:Enhanced: Tropical Forest Diversity--The Plot Thickens David F. R. P. Burslem, Nancy C. Garwood, Sean C. Thomas Ecologists have long pondered why tropical forests contain such a huge number of species and what factors might be responsible for maintaining this diversity. In a Perspective, Burslem and colleagues discuss unique data sets from the forest dynamics plots (FDP) network, which shed light on the factors responsible for tropical forest diversity. D. F. R. P. Burslem is in the Department of Plant and Soil Science, University of Aberdeen, Aberdeen AB24 3UU, UK. E-mail: d.burslem@abdn.ac.uk. N. C. Garwood is in the Department of Botany, Natural History Museum, London SW7 5BD, UK. E-mail: ncg@nhm.ac.uk. S. C. Thomas is in the Faculty of Forestry, University of Toronto, Toronto M5S 3B3, Canada. E-mail: sc.thomas@utoronto.ca