The scheme at Holland Park comprehensive, west London, is a forerunner of the one-stop centres, incorporating schools, health centres and social services, favoured by the Government's social exclusion unit.
Ann Marie Howell has been seconded to the school since October as part of a three-year inclusion project, funded by the local education and health authorities and social services.
Ms Howell, together with a team of two youth workers and an educational welfare officer, has been given the credit for a dramatic reduction in exclusions, which fell to 57 in the six months to February. This compares with 150 in the same period the previous year.
Crisis intervention, mediation and working with parents are all part of her job.
One example of Ms Howell's caseload involved a disruptive pupil facing possible exclusion.
"I discovered the student was the subject of a child-protection case which involved giving eidence to the police about members of the family. The youngster was in crisis. Once the situation became clear the school could respond more appropriately."
On-site social workers are relatively uncommon, according to the Association of Social Services Directors. However, with the Government's attack on social exclusion and its "joined-up thinking" approach, the idea is gaining currency.
Mary Marsh, headteacher of Holland Park, said the scheme was extremely successful. Fixed-term exclusions had dropped dramatically since the team, and other programmes to tackle behaviour, had been put in place.
"Pupils feel they can open up because they are speaking to someone who knows what is going on and having her professional expertise makes staff more confident about what they are doing," she said.
"Communication between the school and social services has also improved hugely.
"I think the scheme is proving to be a powerful model enabling more students to keep focused on what they are trying to do in school."