This bulletin is devoted to the work of the International Problem Area Group (INTERPAG), and is the last of four such bulletins reporting on problem area group research. The first three articles cover the group's work on trade. The first, by Hans Singer, reports on the trade liberalization project which has been centred at IDS and whose first report argued the benefits of increasing trade between developed and under-developed countries. The second article, by Percy Selwyn, is a critique of this approach, principally for practical reasons. The third, by David Evans, presents an alternative theoretical approach for analysing trade relations 'unequal exchange' - which questions among other things the orthodox theory on which proposals for trade liberalization are based.