Approved social worker (ASW) numbers in England and Wales were compared on the basis of two national surveys conducted in 1992 and 2002. These data were supplemented by reports published by the Employers' Organisation in the intervening years. Although raw numbers suggested a modest absolute increase over this time, rates of ASW's per 100,000 population declined by over 50%. Possible explanations for this dramatic fall are explored. The authors conclude that specific and targeted action needs to be taken by the government and public sector employers to determine the numbers of mental health social workers needed in modernised community mental health services.