Tarbush, a deciduous shrub, has rapidly increased its dominance in Chihuahuan Desert grasslands. Encroachment of tarbush has led to a concomitant degradation of forage production, wildlife habitat value, soil stability and watershed quality. Therefore, sustainable methods to reduce the encroachment of tarbush are highly desirable. Since tarbush is comparable to alfalfa in nutrient density, we believe increasing livestock intake of tarbush will improve diet quality, while decreasing tarbush competitiveness. A sheep study was initiated to determine dietary preference for tarbush and influence of previous tarbush exposure on preference. Twenty ewe lambs (10/treatment) were assigned at birth to receive cither tarbush or alfalfa (15%, dry matter basis) in a sorghum-based pelleted creep feed. Lambs were pen-fed this diet 60 days pre-weaning and 60 days post-weaning. No differences existed between treatments in ration consumption. After 120 days, each group was placed in one of two adjacent 45 m² paddocks dominated by tarbush and burrograss (Scleropogon brevifolius). An assessment of individual diet selection was determined visually from an elevated platform at three minute intervals for 4 hours following sunrise on 2 consecutive days, with lambs being alternated to the other paddock on the second day. The observations were repeated every 30 days until dormancy of tarbush. Between each observation period, lambs were pastured in 10 ha paddocks with a similar species composition as the study paddocks. Over the course of the study, lambs were recorded eating tarbush during approximately 35% of feeding observations. Initially, previous exposure to tarbush appeared to avert lambs from tarbush, yet this aversion wan not apparent during later periods.