Management Systems International | 42,329 followers on LinkedIn. MSI, A Tetra Tech Company, is a Washington, DC metro area international development firm with a 30-year history of helping to deliver development results across the developing world. We operate in some of the most challenging political and economic climates in the world, including Pakistan, Afghanistan, South Sudan and Iraq. MSI currently employs 800 development experts in the fields of public sector management, monitoring and evaluation, governance and anti-corruption.