How does forest growth integrate weather, insect and disease attach, management actions, and natural disturbance? Which of these has the most impact on forest growth, composition, structure, and change? These questions have animated the activities of scientists of the Rocky Mountain Research Station (RMRS) since its earliest days, and continue to animate our research today. RMRS is home to some of the first EFRs established in the Forest Service system: (1) Fort Valley Experiment Station was established in 1908 near Flagstaff, Arizona; (2) Fremont EF was established in 1909 on the Fremont and Pike National Forest near Wagon Wheel Gap Experimental Watershed (established 1911) and west of Colorado Springs, Colorado; (3) Priest River Experiment Station was established in 1911 at Priest River EF near Priest River, Idaho; and (4) Utah Experiment Station (now Great Basin Experimental Range) was established in 1912 near Ephraim, Utah. Perusal of the scientific and forest resource management literature, especially in the early to mid-twentieth century, reveals many examples of the research being conducted at least partially on EFRs (Daubenmire 1957; Davis 1942; Gisborne 1922). At one time, the current area of the RMRS contained at least 27 EFRs; the current number is 14.