Technical Abstract: The objective of this study has been to monitor the effects of altered precipitation patterns on plant community dynamics in the sagebrush steppe. Plant community response to altered precipitation patterns were assessed by monitoring plant species cover and density, biomass production, phenological development, and root growth. Five rainout shelters, 100 x 40 ft., were used to control season and amount of precipitation. Precipitation treatments under each shelter are labeled ¿winter¿, ¿spring¿, and ¿current¿. Annual forbs were the most responsive to different treatments. Annual forb density and cover have been consistently lower in the spring treatment compared to the other treatments in all years. Bareground tended to be greater in the spring treatment than in winter and control treatments since May, 1996. Sagebrush phenology has been delayed in the spring treatment through floral shoot development. However, by the ephemeral leaf drop stage there have been few differences in sagebrush phenology among the treatments. In all treatments, root activity appears to be correlated to soil moisture conditions particularly in the upper (10-20 cm) soil profile. during periods of higher moisture availability root activity increases. Although there has been a lack of any consistent treatment effects it does appear that the spring treatment may be allocating more resources to below ground structures.