This paper assesses the impact of central policies on the autonomy of local authorities in Wales since 1979. Several problems in the measurement of central constraints are identified, including the distinction between aggregate and individual autonomy, the specification of central objectives and the need to take account of factors that reinforce or counteract central policies. The behaviour of Welsh local authorities is compared with six central goals: lower spending, less direct service provision, a greater emphasis on market mechanisms, compliance with central targets, less policy diversity and a weaker link between party politics and policy decisions. The empirical evidence provides only limited support for the centralisation thesis. General conclusions are drawn on the conceptualisation and measurement of central constraints on local autonomy.