This chapter provides a synthesis of information on potential supply of forest biomass given needs for sustainable development of forestry. Sustainability includes maintenance of water supply, biodiversity, and carbon storage as well as timber products, community development, and recreation. Biomass removals can reduce fire hazard and insect and disease attack, restore forest composition and structure, enhance forest growth, provide revenue for treatments and communities, and offset greenhouse gas emissions. Biological limitations vary by forest condition, ownership, and how stands are regenerated. Limitations maintain water supply, soil nutrients, and biodiversity. There are economic limitations because costs for removals may exceed revenue. One analysis suggests U.S. forest-based biomass supply could be 45 million dry tons per year or more, depending on biomass price. Social targets and limitations are given in federal and state legislation. These include a federal cellulosic fuel target with biomass source restrictions, state-level renewable energy portfolio standards, and state-level forest practice guidelines. Understanding of biological and economic limitations and benefits is developing, particularly at local levels. Social targets and limitations could change. Increases in fossil fuel prices would accelerate efforts to develop understanding of biological limitations and could result in changes to social and economic targets and limitations.