This book consists of survey and research articles expanding on the theme of the “International Conference on Reaction-Diffusion Systems and Viscosity Solutions”, held at Providence University, Taiwan, during January 3–6, 2007. It is a carefully selected collection of articles representing the recent progress of some important areas of nonlinear partial differential equations. The book is aimed for researchers and postgraduate students who want to learn about or follow some of the current research topics in nonlinear partial differential equations. The contributors consist of international experts and some participants of the conference, including Nils Ackermann (Mexico), Chao-Nien Chen (Taiwan), Yihong Du (Australia), Alberto Farina (France), Hitoshi Ishii (Japan), N Ishimura (Japan), Shigeaki Koike (Japan), Chu-Pin Lo (Taiwan), Peter Polacik (USA), Kunimochi Sakamoto (Japan), Richard Tsai (USA), Mingxin Wang (China), Yoshio Yamada (Japan), Eiji Yanagida (Japan), and Xiao-Qiang Zhao (Canada).Contents:Long-Time Dynamics in Semilinear Parabolic Problems with Autocatalysis (N Ackermann)A Note on Reaction-Diffusion Systems with Skew-Gradient Structure (C-N Chen et al.)Change of Environment in Model Ecosystems: Effect of a Protection Zone in Diffusive Population Models (Y Du)The State of the Art for a Conjecture of de Giorgi and Related Problems (A Farina & E Valdinoci)Threshold and Redistancing Dynamics for Geometric Motions (S Esedoglu et al.)Global Solutions for the Shigesada–Kawasaki–Teramoto Model with Cross-Diffusion (Y Yamada)Dynamics of Global Solutions of a Semilinear Parabolic Equation (E Yanagida)Spatial Dynamics of Some Evolution Systems in Biology (X-Q Zhao)and other papersReadership: Researchers and postgraduate students in partial differential equations and mathematical biology.