A survey of teachers, heads and other school staff across the UK found that 44% believed girls' behaviour had worsened in the past two years.
This compares with 43% for boys, says a survey of 859 members of the Association of Teachers and Lecturers.
But 68% of staff in the survey said boys' behaviour is more difficult.
Half of the surveyed staff thought boys' behaviour had got worse over the past five years, and 48% thought girls' behaviour was worse.'Friendship problems'
One secondary school teacher who contributed to the study said: "Boys are more physically aggressive and usually to other pupils, with girls it is more name calling, less fighting."
For girls, most staff said bullying such as isolating another pupil from a friendship group, spreading rumours, making snide looks and comments, were the biggest problems (44%).
A 34-year-old teacher from Reading, said: "Girls spread rumours and fall-outs last a long time. Boys tend to sort it out fairly quickly."
And a teaching assistant from Weston-Super-Mare said: "Girls are definitely getting more violent, with gangs of girls in school who are getting worse than the gangs of boys."
A Department for Education spokesman said: "Teachers can't teach effectively and pupils can't learn if discipline is poor or there is continual low-level disruption.
"That's why we're giving teachers tough new powers and underlining their clear authority to crackdown on badly-behaved pupils."
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