More school governors in England need to be recruited from ethnic minorities and younger age groups, a charity says.
Governors, who are unpaid, meet several times each term
The School Governors' One-Stop Shop said it was important to "keep up with a rapidly changing environment".
It said non-white governors were often lacking in areas where the schools had many pupils from ethnic minorities.
SGOSS chief executive Steve Acklam also said more applicants needed to have business skills to ensure the smooth running of schools.
He added: "In some areas, 70% of the population of a school can be from an ethnic background."
Mr Acklam also said: "Schools need to keep up with a rapidly changing environment in terms of the current socio-economic and hi-tech climate.
"Having a younger, more diverse generation on board is more important now than ever before."
The group says 40,000 - or 12% - of England's governor places are vacant at any one time.
In more deprived areas, this can rise to 25%, it adds.
Hugh Goulbourne, a mixed-race, 30-year-old lawyer, has been a governor at Lister Community School in Newham - an ethnically diverse part of east London - for almost three years.
He said: "I felt being a school governor would be a good way of giving something back to the community.
"It's a good thing to do because you are doing something different from ordinary work. It gives you a better work-life balance.
"The role takes you away from work and gives you something else."
The SGOSS estimates the average governor spends eight hours in meetings each term.
It hopes to recruit a further 1,500 volunteers by next March.
A Department for Education and Skills spokesman: "We know that a good, diverse governance can make an impact in the classroom.
"Standards of attainment, quality of teaching and pupil behaviour are all likely to be better in schools where governance is good - that is why the School Governors' One-Stop Shop was introduced by this government in 1999."