Stand density management is the process of controlling tree density within a stand to achieve desired objectives. Stand density management practices include the spacing of planted trees, pre-commercial thinning, and commercial thinning. A sound density management prescription must consider three elements of prediction: biological responses of the stand to treatment, economic implications of the treatment, and forest-level effects of the treatment. This document provides essential information on each of these elements, and provides a structured decision process for making site-specific density management prescriptions. Sections of the document cover the biological concepts of timber production, economic principles of timber production, forest planning considerations, the decision process, and density management planning tools. Includes glossary.