This paper reviews moose habitat selection and discusses the environmental factors which affect selection. Moose use open areas and lowlands extensively in spring and early summer in apparent response to snow melt and early green-up in such areas, and possibly to the greater protein content of plants growing there. Increased use of taller more-mature stands in later summer and fall may be associated with a higher protein content of browse beneath a forest canopy. Disturbed sites (burns, logged areas, epidemic areas, windfalls, etc.) and stands of tall shrubs with an abundance of deciduous browse are heavily utilized during early winter and/or periods of low snow depth. Increasing snow depths restrict moose activity and intensify use of areas having dense vegetation and coniferous cover where snow is shallower. This constraint on movement may in part explain the increased consumption of coniferous browse during winter. Altitudinal migrations are frequently observed in mountainous regions. These are probably caused by selection of areas of greater forage quantity and quality, in addition to lesser snow depths during winter. Other factors that may affect moose habitat selection include the availability of escape cover and mineral licks.