The historic preservation field is aggressively promoting itself as "green." Adaptive reuse of historic buildings is now widely considered a sustainable development practice. As with architecture in general, however, sustainability in preservation is too often narrowly framed around environmental issues such as the conservation of materials, energy, and water. Commonly accepted definitions of sustainability recognize two other components: economics and culture. Rarely does the preservation field consider sustainability as an entire system of interrelated environmental, economic, and social relationships, as envisioned by the Brundtland Report of 1987. This article offers several reasons for the preservation field to engage in the full spectrum of sustainability concerns, including economic and social issues. It then reexamines one of most famous case studies in the canon of historic preservation in the United States—Faneuil Hall Marketplace in Boston—to consider the extent to which sustainability was addressed as a system of interrelated relationships. In conclusion, it suggests that preservation could be made more sustainable by drawing connections among several existing concepts, findings, and methods developed by Randall Mason, Setha Low, and others.