Hal Caswell is a Senior Scientist in the Biology Department at the Woods Hole Oceanographic Institution, where he holds the Robert W. Morse Chair for Excellence in Oceanography. He earned a Ph.D. in Zoology in 1974 at Michigan State University. In addition to Matrix Population Models, Dr. Caswell is a coauthor (with S. Tuljapurkar) of Structured Population Models in Marine, Terrestrial and Freshwater Systems (Chapman and Hall, 1997). A former Guggenheim Fellow and a Fellow of AAAS, he has also served as Chairman of the Theoretical Ecology Section of the Ecological Society of America. Dr. Caswell's research interests include mathematical ecology, structured population models, stochastic models for spatial processes, conservation of marine mammals and seabirds, plant population ecology, ecotoxicology, and nonlinear dynamics in ecology.