“What joy to discern the minute in in?nity, the vast to perceive in the small, what divinity!” Jacob Bernoulli (1654-1705) in Ars Conjectandi (1713) We are proud to present to you the proceedings of the Sixth International C- ference on Cellular Automata for Research and Industry (ACRI 2004), held in Amsterdam, The Netherlands on October 25–27, 2004. Since the ?rst conference in Italy, ACRI, which is held biennially, has become the premier conference in the ?eld of cellular automata in Europe and beyond, and is still growing in quality and size. This year’s theme was “From Individual to Collective Behavior”, emphas- ing the capability of Cellular Automata to simulate macroscopic processes from individual, local interactions. Cellular Automata, in spite of their apparent s- plicity, represent a very powerful approach to studying spatio-temporal systems in which complex phenomena build up out of many simple local interactions. In thewordsofRichardFeynmanintheCharacterofPhysicalLaw(1982),“Nature uses only the longest threads to weave her patterns, so each small piece of her fabric reveals the organization of the entire tapestry”. John von Neumann, who is recognized as the father of cellular automata, would have been 100 years old in 2004. ACRI 2004 wanted to commemorate this date by inviting researchers to submit contributions related to von Neumann’s work or to the emergence of organization in systems in which collaboration between components wins over the individual behavior.