The investment seeks to track the performance of the Calvert Global Water Research Index. The fund normally invests at least 80% of its net assets in equity securities of U.S. and non-U.S. companies whose main business is in the water industry or that are significantly involved in water-related services or technologies. The index is composed of companies that manage water use in a sustainable manner or that are actively engaged in expanding access to water, improving water quality, promoting efficient use of water, or providing solutions that address other global water challenges.