Pith-to-bark increment cores were obtained at breast height from 199 interior Douglas-fir parent trees located in the east Kootenay region of British Columbia. The cores were divided into equal lengths and were analyzed separately for wood density. The half portion close to the pith (inner half) was used to estimate the juvenile wood density; the outer half was used to estimate the wood density of the mature volume of the tree. The outer half was significantly higher in wood density than the inner half. When compared to other parent trees of the same species located in other interior seed zones, the outer half of these east Kootenay trees had significantly lower wood density.