Trade and investment are too important to be left out of national development strategies as they exert powerful effects, direct and indirect on poor people and poor countries. Even if the overall effect is positive, some groups may be adversely affected, and analysis must take into account the interaction between economic flows and policy responses. The poor and the non-poor themselves may adapt their behaviour to any incentive or shock from trade – but as our work in Africa shows, there are real differences in opportunities to participate in the new world economy.