This paper explores the evolution of the largest non-governmental organization to serve in Vietnam, International Voluntary Services (IVS), from the perspective of three of its volunteers. All had served for substantial periods and were in positions of responsibility by September 1967, when they resigned in an open letter protesting American policy sent to President Lyndon B. Johnson. The letter was the product of their experiences and discussions, and expressed sentiments shared by an overwhelming number of their fellow volunteers, many of whom signed the letter in sympathy. Upon publication in the New York Times, the letter became a subject of controversy in Saigon and Washington, as the resignations were the first protest from within the American community in Vietnam. Perhaps as important, the resignations were the culmination of a process of reflection and growth that led the signers to a new understanding of social responsibility and activism.