Chastain is founder and CEO of Mann Global Health, a mid-sized consulting firm with a roster of roughly 40 associates and senior associates who work in global health and development. Chastain is a strategy expert, including organizational strategy, fund raising and growth strategies, and organizational development. She works closely with chief executives and management teams to help non-profit organizations envision and plan for improvements in their support to the people they serve. Chastain has 30 years of experience designing, supervising, implementing and evaluating programs in sexual and reproductive health, HIV, MNCH, malaria, and disaster relief. She lived and worked in Africa for more than 10 years, including stints as a USAID contractor in Zambia and Mali, and as the PSI Country Representative in Togo and Uganda.

In 2006 she became VP of PSI’s business development department as well as its advocacy department. At Woman Care Global, a non-profit focused on launching new SRH products, Chastain was Chief of Programs and Strategy, and also Director of its USAID-funded EECO Project (Expanding Effective Contraceptive Options), which launches and tests new contraceptives. At Mann Global Health, Chastain leads teams of experts with complementary skills to take on complex projects in global health. Clients include a wide range of international NGOs, as well as donors such as The Bill & Melinda Gates Foundation, CIFF, The Global Fund, and USAID.