Today, more than ever, efficient use of water by the agricultural sector is critical to sustaining national and global food security in both irrigated and rainfed regions. Implementing deficit irrigation (DI) strategies and site-specific irrigation management can improve crop water productivity without significantly reducing yield. Under some conditions, these management practices can also result in water conservation, while advanced technologies can facilitate environmental stewardship. This chapter describes the main DI strategies used in agriculture and reports on results from current studies using DI strategies, as well as the status for site-specific irrigation management and its role in minimizing agricultural water use.