Changes in the climate and in key ecological processes are prompting increased debate about ecological restoration and other interventions in wilderness. The prospect of intervention in wilderness raises legal, scientific, and values-based questions about the appropriateness of possible actions. In this article, we focus on the role of science to elucidate the potential need for intervention. We review the meaning of "untrammeled" from the 1964 Wilderness Act to aid our understanding of the legal context for potential interventions in wilderness. We explore the tension between restraint and active intervention in managing wilderness and introduce a framework for testing ecological assumptions when evaluating restoration proposals. We illustrate use of the framework in the restoration of fire regimes and fuel conditions in ponderosa pine and mixed-conifer forests of the US Rocky Mountains. Even in this relatively well-studied example, we find that the assumptions underlying proposed interventions in wilderness need to be critically evaluated and tested before new, more intensive management paradigms are embraced.