The Plus/Minus Dilemma was the third roundtable discussion in the ongoing IIC series Dialogues in the New Century; events that explore emerging issues in the modern world and their relationship to heritage conservation. The event took place at the Midwest Airlines Convention Center in Milwaukee, Wisconsin on May 13, 2010 as part of the AIC annual conference. The IIC is pleased to have collaborated with the AIC to have brought together experts to discuss environmental guidelines, advances in environmental research, and the way forward to solve the plus/minus dilemma. This collaborative event has been made possible by the generous support of: The Booth Heritage Foundation, the Foundation of the American Institute for Conservation, the Institute for Museum and Library Services, and the Samuel H. Kress Foundation.