This report presents an overview of the El Yunque National Forest, which is also designated as Luquillo Experimental Forest, in northeastern Puerto Rico. The principal topics include the environmental setting (geology, soils, and climate), environmental gradients, arborescent flora, vertebrate fauna, and forest management (i.e., plantations, silvicultural operations, planning, research, and designated land uses). A chronology from the time of European discovery to the present outlines major events in the Luquillo Experimental Forest, including an early presence of indigenous peoples, exploration for gold, timber extraction, farming, trail and road construction, and recreational developments.