Technical Abstract: Efficiency in water usage is important for the long-term viability of peanut production in West Texas and New Mexico. Rainfall (18 inches annually) must be supplemented by irrigation in this region, but depletion of groundwater requires greater efficiency in future water usage. To determine components of tolerance to abiotic stress, twenty runner and four Spanish! Valencia accessions were planted in a replicated experiment at Denver City, Texas in 2002. Accessions were evaluated under 'irrigated' (75% evapotranspiration replacement) and 'drought' (50% ET replacement) conditions. Significant differences in flowering were observed between treatments for all but the first and last measurement dates, with reductions ranging from 10% to 77%. Significant differences were observed among genotypes also. Canopy temperature was 2.9 to 4.3 C cooler for irrigated than drought treatments, with differences being observed among genotypes. Significant differences in biomass accumulation occurred among treatments and genotypes, and GxE interactions were observed. Differences in osmotic potential occurred between treatments for Spanish/Valencia accessions, but genotype differences were not observed. We conclude that there are several different responses among accessions to reduced irrigation, and some of these may prove useful in a selection program.