The management of national park and wilderness areas dominated by forest ecosystems adapted to frequent, low-intensity fires, continues to be a tremendous challenge. Throughout the inland West and particularly in the Southwest, ponderosa pine (Pinus ponderosa) and mixed conifer forests have become dense and structurally homogeneous after periods of intense livestock grazing, followed by more than 100 years of fire suppression. Prior to the late 1800s, pine-dominated forests at Grand Canyon National Park were structurally diverse, averaging 45 to 90 trees per acre, with frequent, low-intensity fires burning across the landscape every 7 to 11 years. Today, much of the historic landscape heterogeneity has been replaced by dense, contiguous stands averaging 600 to 900 trees per acre. The beneficial reintroduction of fire to these areas is difficult and often results in fire effects that are uncharacteristic of those produced by historic fire regimes. In response, park managers have called for the exploration of restoration approaches using combinations of prescribed fire and understory thinning. The goal of this approach is to achieve more natural and sustainable forest structures while conserving the most fragile elements of the existing ecosystem such as old-growth trees and native herbaceous communities. This paper describes the approach, rationale and preliminary results of a project designed to examine the utility and ecological effects of three, small-scale restoration experiments on a suite of forest structure attributes.