This paper describes the construction of an accounting matrix for the world economy in 1977, cast along similar lines to SNA National Accounts, but one in which trade flows replace inter‐industry flows as intermediate demand. The matrix distinguishes ten regions. Institutional accounts are presented for three of these, the European Community, North America and Japan. This matrix is used to provide the basis of a linear model in which average propensities to import and consume are replaced by estimated marginal propensities. Use is made of standard estimates of the income effects of terms of trade changes in order to distinguish substitution from income effects in the model, and a means is suggested for separating the full as well as the impact effects of a terms of trade change into income and substitution effects. The estimated import equations are used to derive estimates of regional growth rates compatible with external balance in each region. Multiplier matrices are calculated from the model showing regional interdependence of the world economy reflecting the pattern of trade which is identified in the marginal propensities to import.The effects of various aid policies are calculated using the model. It is shown that the cost of aid to any region is radically altered by taking into account the feedback effects of changes in demand. A policy of tied aid pursued by EEC, North America and Japan can actually lead to an improvement in Japan's balance of payments position. Finally the effects of movements in relative prices are illustrated by means of two example