In a speech in 1978 Sir Douglas Wass of the British Treasury described how condidently demand management was practised up to the end of the 1960s.. Now, however, governments are much less confident about the desirability of expanding aggregate demand even when there is considerable unemployment. There are, moreover, many voices crying for fiscal contraction in the UK at the present time when unemployment is high relative to what it was in the 1950s and the 1960s. It would appear that aggregate demand is no longer being set to achieve target levels of employment. What is checking the use of demand management? What are now regarded as the effective constraints on how far output should be expanded?