The Editor of Artificial Life would like to express his gratitude to the people listed below, who anonymously reviewed papers for the journal during the preparation of Volume 20. Their generosity, judicious judgment, and prompt response substantially helped us publish a journal that both is timely and has exacting scientific standards. The responsibility for sustaining the quality and relevance of the journal rests largely in the hands of our reviewers. We at the journal, and all of our readers, are deeply indebted to them. It is a genuine pleasure to thank them collectively for their dedicated service. (If anyone has been inadvertently omitted from this list, we sincerely apologize and ask them to let us know so that we can include their name in a future list of reviewers.)

Lee Altenberg

Ricardo Azevedo

Tony Belpaeme

Hugues Bersini

Mauro Birattari

Paul Bourgine

Tamás Czárán

Joachim De Beule

Ezequiel Di Paolo

Anna Deplazes

Marco Dorigo

Alan Dorin

Rene Doursat

Arantza Etxeberria

Harold Fellermann

Carlos Gershenson

Mario Giacobini

Didier Gonze

Martin Hanczyc

Phil Husbands

Takashi Ikegami

Colin Johnson

Eric Klavins

Daniel Lobo

Ranjan Mannige

Olivier Martin

Barry McMullin

Stefano Nolfi

Joshua Payne

Jorge Peña

Rashid Rashidzadeh

James Reggia

John Rieffel

Hiroki Sayama

Thomas Schmickl

Roberto Serra

Russell Standish

Pasquale Stano

Susan Stepney

Chris Takahashi

Tim Taylor

Gunnar Tufte

Reidun Twarock

Nathaniel Virgo

Liyu Wang

Borys Wrobel

Andy Wuensche

Tom Ziemke