We were very pleased to choose papers for presentation at the ACM-SIAM Symposium on Discrete Algorithms (SODA), which will take place in Manhattan in January 2009. A total of 550 short abstracts were submitted, later materializing into 458 submissions, of which 135 were selected. The program committee meeting was entirely electronic and the selection process took place in July and August 2008. The Best Student Paper award was given to the paper "Improved Bounds and New Techniques for Davenport?Schinzel Sequences and Their Generalizations" by Gabriel Nivasch, and the Best Paper award was given to the paper "Natural Algorithms" by Bernard Chazelle. There will be three invited presentations: one by Volker Strassen, as the recipient of the ACM-SIGACT 2008 Knuth prize; one by Michael Jordan; and one by Yuval Peres.