This research studies Finnish private forestry in the 1900s. The period in question was a time during which private forestry gradually adopted the principles of sustainable wood production. At the same time, private forests became the most important source of raw material for the industry. Development in the 1900s meant that private forestry moved from dimension felling to sustainable forestry methods. This development will be described by studying the development of private ownership, private forest resources and harvesting in private forests - all the way from the beginning of 1900s to the turn of millennium. Furthermore, the study will look at public forest policies aimed at private forestry, the ecological, economical and social substainability of private forestry and the new challenges for practicing private forestry.