Biomass, a renewable energy source, has been viewed as “carbon neutral”—that is, its use as energy is presumed not to release net carbon dioxide. However, this assumption of carbon neutrality has recently been challenged. In 2010 two letters were sent to the Congress by eminent scientists examining the merits—or demerits—of biomass for climate change mitigation. The first, from about 90 scientists (to Nancy Pelosi and Harry Reid, from W.H. Schlesinger et al. May 17, 2010), questioned the treatment of all biomass energy as carbon neutral, arguing that it could undermine legislative emissions reduction goals. The second letter, submitted by more than 100 forest scientists (to Barbara Boxer et al. from Bruce Lippke et al. July 20, 2010), expressed concern over equating biogenic carbon emissions with fossil fuel emissions, as is contemplated in the Environmental Protection Agency’s Tailoring Rule. It argued that an approach focused on smokestack emissions, independent of the feedstocks, would encourage further fossil fuel energy production, to the long-term detriment of the atmosphere. This paper attempts to clarify and, to the extent possible, resolve these differences.