Teachers' subject associations are battling a serious decline in membership, a TES analysis of their latest accounts has revealed.
The largest annual fall was recorded by the Association for Language Learning, which shed 14 per cent of its members in the academic year 20067.
Numbers at the Geographical Association have also halved in the past 10 years, while the National Association for the Teaching of English has seen a 40 per cent drop over that period.
Many leading figures within the associations attribute the general downward trend to the increase in Government control over education in the past 20 years, starting with the establishment of the national curriculum in 1988.
They believe this has meant that teachers have been less inclined to join an association to formulate their own ideas on what works in the classroom.
Derek Bell, outgoing chief executive of the Association for Science Education, said: "The greater the hold the Government has taken over the curriculum, the more people have been encouraged to think there is only one way to teach."
He added: "I just feel that there are times when the Government, and others, could have made a much bolder statement about the benefits of joining a subject association."
Professor Bell, who is leaving the association to become head of education at the Wellcome Trust charity, said that bodies such as his had taken initiatives - for example, setting up a Chartered Science Teacher professional grade - but they needed more support.
He added that many science advisers working on National Strategies programmes in local authorities were not members of a subject association, which was a great shame.
The Government set up a Council for Subject Associations last year, in a drive to improve their standing.
David Jones, its chief executive, said that while he shared concerns over the underlying trends, several associations had reported improving membership figures in recent months.
He said the associations had taken steps to turn their fortunes around, including recruitment drives to attract trainee teachers. And they saw the initiatives, such as the masters in teaching and learning qualification, as an opportunity to stress their relevance to teachers' continuing professional development.
The Association for Language Learning said its numbers had rallied in 2007-8, partly driven by a free membership offer to PGCE students and newly qualified teachers, which has brought in 642 young recruits since 2006. The association now estimates that around a third of secondary school language teachers are members.
Subjects struggle, pages 20-21.