As global climate change becomes inevitable, the sustainability of agricultural production in US and worldwide faces serious threat from extreme weather conditions, such as drought and high temperature (heat wave). Development of drought and/or heat tolerant crop varieties is one of the most effective ways to mitigate the negative impacts associated with climate change on crop production. Drought and heat tolerance in plants are very complex traits. To dissect the genetic factors that contribute to these traits, we have configured various methods and screened maize and sorghum germplasm for drought and/or heat tolerance.  Sorghum accessions that use water efficiently (more biomass production per unit water used) were identified and characterized. These accessions may provide genetic materials to breed for sorghum varieties/hybrids that increase sorghum yield in arid and semi-arid regions and sustain sorghum yield under no or very limited irrigation. Heat tolerant maize lines were also identified. Studies showed that maize hybrids made from heat tolerant parents grew and developed normally under extreme high temperature weather conditions (heat waves) whereas, hybrids from heat sensitive parents showed various heat-induced tissue injuries, reduction in biomass production and yield.  Genetic study is underway to dissect the mechanisms contributing to drought and/or heat tolerance in maize and sorghum.