1953 mu na Mensah firii adwuma ase sɛ Assistant Inspector of Taxes berɛ a na Gold Coast da so hyɛ Eyeresi aban ase. Afe 1958 na Mensah kɔyɛɛ adwuma wɔ United Nations Secretariat wɔ Centre for Development Planning, Projections and Policies, wɔ New York City, a ɛwɔ Amerika.