The Laboratory of Tree-Ring Research was organized in 1937 as an outgrowth of the pioneering tree-ring studies initiated by Andrew Ellicott Douglass at the University of Arizona in 1906. A division of the College of Arts and Sciences, the Laboratory conducts a unique program of teaching and research in all aspects of dendrochronology. Graduate-level instruction is offered through cooperating academic departments, and a limited number of graduate research assistantships are available to qualified students. Current research efforts are directed toward the quantification of tree-ring parameters, the establishment of new tree-ring chronologies throughout the world, the use of tree-rings in the study of forest ecosystems, the reconstruction of paleohydrologic and paleoclimatic variables, and the documentation and development of prehistoric chronological controls. Along with the world's largest collection of tree-ring specimens from living trees and ancient timbers, the Laboratory maintains a variety of specialized equipment and data files containing processed tree-ring chronologies, relevant climatic and hydrologic records, and archaeological tree-ring dates and site information. Sponsored research is currently funded by several agencies, including the National Science Foundation, the National Oceanographic and Atmospheric Administration, the USDA Forest Service, the Biological Resources Division of the U.S. Geological Survey and the USDI National Parks Service. The Laboratory has a privately funded program of training in dendrochronology which provides for both short term training visits, and, on occasion, a graduate fellowship.