Fewer teenagers than ever are studying languages, a new report for Cilt, the National Centre for Languages, has warned.
The findings come despite widespread hope last year that the fall in 14-year-olds taking up French, German or Spanish had tailed off.
The survey found a large amount of innovative work being done to promote languages, such as introducing new languages or courses, bringing in outside speakers, and working with universities and football clubs. But the biggest impact on take-up came from changing the school's policy towards languages.
The study, of 668 schools, also found that the proportion of schools where more than half of pupils study languages in Year 10 has fallen from 45 per cent to 40 per cent.
The Government made languages optional for 14 to 16-year-olds in 2004, saying that it would give schools more flexibility over what courses to offer.
By 2005, the dramatic fall in numbers taking languages prompted the then schools minister Jacqui Smith to ask all schools to set a benchmark of at least 50 per cent of pupils studying languages post-14. The study found that this has been widely abandoned as unrealistic.
Kathryn Board, chief executive of Cilt, said: "The need for our young people to learn languages has never been greater, with language skills becoming increasingly important when competing for jobs in the global marketplace. This report shows that young people are enthusiastic about learning languages but the system can be an obstacle".
One teacher responding to the survey said: "More pupils would take a language but so many children want to get As and A*s at GCSE. No amount of talks from external providers or former students can convince them to take a language; they want a guaranteed pass."
Another teacher responded: "At this school there are almost 20 subjects to choose from and even the most popular does not get that."
Last year, 188,688 pupils took French GCSE, compared with 331,089 in 2003. German has plummeted from 125,663 to 73,469 over the same period. Although Spanish entries have risen from 61,323 in 2003 to 67,070 last year.
The survey indicates that for the first time, more maintained schools offer Spanish than German. In the independent sector, Spanish overtook German in 2007, and there is also a growth in other languages. Mandarin is now offered in 40 per cent of independent schools surveyed and 16 per cent of state schools. Italian is also offered in 19 per cent of state schools and 37 per cent of independent schools.
Linda Parker, director of the Association for Language Learning, said: "Language teachers are working to turn things around and interest more children, but often it is external factors or whole-school policies that determine whether pupils enter for GCSE language exams."