This paper outlines a broad and flexible framework for ecological restoration of Southwestern ponderosa pine forests, supporting a diverse range of scientifically viable restoration approaches. Ponderosa pine forests in the region have been radically altered by human uses, particularly livestock grazing, fire suppression, and logging. Old-growth and biodiversity have declined, dense thickets of young trees now abound, and human and ecological communities are increasingly vulnerable to destructive crown fires. A broad consensus has emerged that it is urgent to restore more natural conditions to these forests. Restoration efforts will involve extensive projects employing varying combinations of young tree thinning and reintroduction of low-intensity fires. Treatments must be flexible enough to recognize and accommodate: high levels of natural heterogeneity; the dynamic nature of ecosystems; wildlife and other biodiversity considerations; scientific uncertainty; and the challenges of on-the-ground practices. Ecological restoration should reset ecosystem trends toward an envelope of "natural variability”, including the reestablishment of natural processes. Reconstructed historic reference conditions are best used as general guides rather than as overly-precise and rigid restoration prescriptions. Impatience, extractive economics, or hubris could lead to widespread application of highly intrusive treatments that might further damage forest ecosystems. Investments in research and monitoring of restoration treatments are essential to refine restoration methods. We propose vigorous, locally-adapted restoration approaches that incrementally return natural variability and resilience to Southwestern forests.