This collection of original essays reflects the breadth of current research in computer science. Robin Milner, a major figure in the field, has made many fundamental contributions, particularly in theoretical computer science, the theory of programming languages, and functional programming languages. Following a brief biography of Milner, the book contains five sections: Semantic Foundations, Programming Logic, Programming Languages, Concurrency, and Mobility. Together the pieces convey a seamless whole, ranging from highly abstract concepts to systems of great utility. Contributors: Samson Abramsky, J. C. M. Baeten, Sergey Berezin, J. A. Bergstra, Gérard Berry, Lars Birkedal, Gérard Boudol, Edmund Clarke, Pierre Collette, Robert L. Constable, Pierre-Louis Curien, Jaco de Bakker, Uffe H. Engberg, William Ferreira, Fabio Gadducci, Mike Gordon, Robert Harper, Matthew Hennessy, Yoram Hirshfeld, C. A. R. Hoare, Gérard Huet, Paul B. Jackson, Alan S. A. Jeffrey, Somesh Jha, He Jifeng, Cliff B. Jones, Cosimo Laneve, Xinxin Liu, Will Marrero, Faron Moller, Ugo Montanari, Pavel Naumov, Mogens Nielsen, Joachim Parrow, Lawrence C. Paulson, Benjamin C. Pierce, Gordon Plotkin, M. A. Reniers, Amokrane Saïbi, Augusto Sampaio, Davide Sangiorgi, Scott A. Smolka, Eugene W. Stark, Christopher Stone, Mads Tofte, David N. Turner, Juan Uribe, Franck van Breugel, David Walker, Glynn Winskel.