Marc was one of the very earliest critics of the new human genetic technologies, beginning with his work at the Hastings Center in the early 1970s. Thirty years later, he participated in the exploratory meetings that eventually led to the Center for Genetics and Society, presented at our briefing for funders at the Rockefeller Foundation in January 2001, and spoke at the symposium we held with Bill McKibben in San Francisco in April 2003. Marc was executive director of CETOS, a public interest organization working to protect vulnerable populations from the harmful effects of environmental hazards. He was a socially committed scientist and thinker throughout his entire life. We will miss him. See this fine tribute to Marc by his son, Alan.