The Environmental Protection Agency's (EPA) overarching mission is to protect human health and the environment by implementing and enforcing the laws intended to improve the quality of the nation's air, water, and lands. EPA's policies and programs affect virtually all segments of the economy, society, and government. As such, it operates in a highly complex and controversial regulatory arena. In recent years, GAO's work has identified several significant and persistent challenges across a range of EPA programs and activities and has proposed corrective actions to enable the agency to more effectively accomplish its mission. Based on this work, this testimony highlights some of the major management challenges facing EPA today, the agency's efforts to address them, and the work GAO believes remains to be done.