The Editor of Artificial Life would like to express his gratitude to the people listed below, who anonymously refereed papers for the journal during the preparation of this volume (Vol. 18). Their generosity, judicious judgment, and prompt response substantially helped us to publish a journal that both is timely and has exacting scientific standards. The responsibility for sustaining the quality and relevance of the journal largely rests 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 anyone 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 referees.)

Arturo Araujo

Buzz Baum

Jarle Breivik

Angelo Cangelosi

Anton Crombach

Ezequiel di Paola

Alan Dorin

Rene Doursat

Keith Downing

Peter Durr

Chrisantha Fernando

Anthony Fingelkurts

Tom Froese

Ruedi Fuchslin

Nic Geard

Carlos Gershenson

Patrick Grim

Paul Higgs

Andrew Horchler

Axel Hunding

Tim Hutton

Martin Nilsson Jacobi

Christian Jost

Laurent Keller

Serge Kernbach

Johannes Knabe

Blake LeBaron

Armin Mikler

Julian Miller

Rob Mills

Jean-Baptiste Mouret

Ryan Muldoon

Jason Noble

Daniel Polani

Simon Powers

Craig Reynolds

Francisco Romero-Campero

Hiroki Sayama

Russell Standish

Ken Stanley

Reiji Suzuki

Uwe Tangen

Panos Trahanias

Christof Tuescher

James Watson

John Welch

Steffen Wischmann

Larry Yaeger

Jason Yosinski