Nearly half of the pupils at Cardinal Hinsley Roman Catholic high school for boys are African-Caribbean.
Richard Kolka, lead deputy headteacher at the 415-pupil school in north London, said: "We have hard-working and high-achieving African-Caribbean boys, but we do have problems with some not wanting to work.
"They find it hard to concentrate for long periods and work in short bursts.
"Many come from single-parent families and although they are keen that their sons do well, their circumstances mean they are stretched.
"Trying to engender a work and achievement culture is our challenge."
At Cardinal Hinsley, the African-Caribbean boys in Years 7 and 8 are mentored by members of staff and the older high-achieving black pupils.
Interest in music and sport is also encouraged at the school by taking them to Fulham football club, playing football with the older pupils at lunchtimes and allowing them to mix music during their weekly mentoring sessions.