The first survey since cannabis was changed from a Class B to a lower Class C drug found that fewer 11- to 15-year-olds in England had used it in the past year. Eleven per cent of pupils took cannabis in 2004, down from 13 per cent in 2001, 2002 and 2003.
Cannabis continued to be the drug children were most likely to have taken, followed by glue, gas and other volatile substances. Four per cent of young people had taken a Class A drug.
The survey, carried out by research organisations NatCen and the National Foundation for Educational Research, also looked at smoking and drinking.
The proportion of children who drank alcohol in the past week had also gone down, from 25 per cent in 2003 to 23 per cent in 2004.
In previous surveys boys were more likely to have drunk alcohol in the past week. But for the first time since the data has been collected, there was no difference between boys' and girls' drinking.
The proportion of boys who had drunk in the past week was at its lowest since 2000, while the proportion of girls who had done so remained stable.
Most children who had consumed alcohol in the past week had done so on one or two days with weekends being the most popular days for drinking.
A quarter of young people who had drunk in the past week had consumed 14 or more units and almost half of the children questioned had been drunk.
Girls are now more likely to smoke than boys. The survey found that a tenth of girls were regular smokers compared with 7 per cent of boys. But both sexes report smoking a similar number of cigarettes, around 42 a week.
Research director Liz Fuller said, 'These finding are important because they contradict several common perceptions.
'The reclassification of cannabis hasn't led to an explosion in the use of the drug and girls aren't drinking significantly more now than they have in previous years.'