Leo Isaac was a ranger and researcher specializing in Douglas Fir silviculture for the United States Forest Service. Isaac was born in 1892 and raised on a Wisconsin farm that was surrounded by woodland and later in WWI served in the Tenth Engineers which was a forestry regiment. After the war he became a junior forester on the Okanagan Chelan where he investigated homestead claims and managed timber sales. From there he transferred to the Pacific Northwest Forest Experiment Station and began work on Douglas Fir seed flight research. Later he worked on space testing, species improvement, heredity study, genetics projects and the Second Growth Committee. Isaac also was part of a Food and Agricultural Organization mission to Turkey for the United Nations and was a private consultant for Manning Seed Company. In this interview, Isaac discusses his education, time as junior forester, experiences at a lumber camp, social life on the Okanagan National Forest, range management, timber sales, life at the Pacific Northwest Forest Experiment Station, Wild River arboretum, partial cutting controversy, problems with updating genetic books, and work in Europe and Turkey. This interview is part of a group of interviews documenting forest history in the United States.