The recent trial in Hawaii of a social and character development curriculum - that has been in action in schools across the globe for nearly a quarter of a century - finally provides solid evidence that it helps children keep clear of sex, drugs and violence.

Positive Action aims to improve academic achievement and behavior. It has been in use since 1982, and is now in 13,000 schools across the US. But it has been working away all this time without any definitive proof that it is effective.

Previous trials of the program - using quasi-experimental methods - have pointed towards a positive effect on exam results and serious behavior issues. However, this type of research design can only show the potential impact of an intervention, it cannot prove definitively whether it works.

But now the results from the first truly rigorous study are in, and they are decisively positive.

A research team from Oregon State University evaluated the effect of Positive Action over a five-year period in 20 elementary schools in Hawaii. They found that children who had received the curriculum were much less prone to drug abuse, violence and sexual activity.

Reported in the American Journal of Public Health, the study says that by age ten, children who had gone through school receiving the program were half as likely to be demonstrate this type of behavior.

The results are extremely impressive when compared with other school-based prevention initiatives. Most similar programs achieve an effect size - a statistic used to compare the relative impact of diverse interventions - of between 0.2 and 0.3. Positive Action recorded 0.34 based on teacher reports, and a whopping 0.73 according to children's self-reports.

Children at the Positive Action schools received short daily classroom sessions focusing on topics like self-management, getting on with others and self-improvement. This included activities and role-plays which encouraged interaction between pupils and teachers.

But why was Positive Action so successful compared to other similar projects? The researchers behind the study have several theories, based on evidence from other studies.

They say that the interactive teaching methods at the heart of Positive Action have been shown to be more effective then traditional methods.

The program was also implemented across the school, in every classroom at the same time, from those starting school for the first time, up to age ten. This meant that all the children, staff and parents at the school were involved simultaneously, creating a supportive school-wide environment.

They also suggest Positive Action’s success was down to the intensive ‘dose’ children received, spending approximately an hour a week on the curriculum.

Other findings from the study back this suggestion up. The behavior of children who entered Positive Action schools after the first year also improved, but not to the same extent as those who had received the program from the beginning. The more involved a child was in the program, the more their behavior improved.

The schools included in the study were all performing poorly academically and catered for many children from deprived backgrounds. Schools were put into pairs, on the basis of demographic similarities, and one of each pair was randomly assigned to implement the intervention.

The study included children who started school in 2001/2002, and stayed there until aged ten, and any others who joined the school in the interim.

Children were asked to fill in a standardized survey about their behavior which was compared with teacher reports.

Another RCT is currently under way in Chicago, which will look at possible effects on academic achievement. This and further research may provide more hard evidence on the benefits of Positive Action.

See: Beets, MW, Flay BR, Vuchinich S, Snyder FJ, Acock A, Li K, Burns K, Washburn IJ & Durlack J (2009), ‘Use of a Social and Character Development Program to Prevent Substance Use, Violent Behaviors and Sexual Activity Among Elementary-School Students in Hawaii’, American Journal of Public Health, 99, 8