Reference conditions describe attributes of ecosystem structure, composition, and function and are used to inform ecological restoration efforts. Reference condition information on tree spatial patterns that occurred prior to wide-spread fire exclusion is limited for warm/dry mixed-conifer forests of the western U.S., particularly those in the Southwest. Spatial patterns of trees, and groups of trees, are important because they are known to influence understory biodiversity and productivity, fire behavior, distribution of surface fuels, wildlife habitat value, and regeneration, yet this information is rarely quantified. The purpose of this fact sheet is to provide an overview of the existing research on spatial patterns in warm/dry mixed-conifer forests, and provide recommendations of future research.