Serge Lang was an iconic figure in mathematics, both for his own important work and for the indelible impact he left on the field of mathematics, on his students, and on his colleagues. Over the course of his career, Lang traversed a tremendous amount of mathematical ground. As he moved from subject to subject, he found analogies that led to important questions in such areas as number theory, arithmetic geometry and the theory of negatively curved spaces. Lang's conjectures will keep many mathematicians occupied far into the future. In the spirit of Lang’s vast contribution to mathematics, this memorial volume contains articles by prominent mathematicians in a variety of areas, namely number theory, analysis and geometry, representing Lang’s own breadth of interests. A special introduction by John Tate includes a brief and engaging account of Serge Lang’s life. Contributors to the volume: D. Abramovich A. Agashe D. Bertrand E. Brenner A. Buium G. Chinta A. Constantin J. Dodziuk M. van Frankenhuijsen W. Goldring B.H. Gross P.E. Gunnells P. Ingram J. Jorgenson A. Karlsson N.M. Katz M. Kim H. Kisilevsky D.Y. Kleinbock B. Kolev J. Kramer S. Lang J. Lubin G.A. Margulis J. McGowan P. Michel M. R. Murty V.K. Murty M. Nakamaye C. O’Neil J.A. Parson P. Perry A.-M. von Pippich F. Pop D. Ramakrishnan K.A.  Ribet D.E. Rohrlich J.H. Silverman A. Sinton W.A. Stein L. Szpiro J. Tate T.J. Tucker M.-F. Vignéras P. Vojta M. Waldschmidt.