'In public policy making, many suppliers and users of social research are dissatisfied, the former because they are not listened to, the latter because they do not hear much they want to listen to'.1 This is the point of departure for a recent book by Charles Lindblom and David Cohen entitled Usable knowledge: Social science and social problem solving. The book has much of interest to planners. Lindblom is probably best known for the concept of planning as disjointed incrementalism or muddling-through and the underlying philosophy of his other works (including The intelligence of democracy, A strategy of decision and Politics and markets) is also apparent in usable knowledge.2 He says 'The stimulus that gives rise to this book is dissatisfaction with social science and social research as instruments of social problem solving'.3