Principals are calling for more early intervention before children start kindergarten because they say many primary schools are struggling to cope with increasing numbers of students who lack basic social skills.

WA Primary Principals Association president Stephen Breen said leaders of most schools he had visited since classes resumed this month had noted a gradual increase in students who had been severely traumatised or abused, which affected their social development.

Mr Breen said one school reported that out of a kindergarten class of 20 students, seven wore a nappy at least once a week.

Teachers at another school said many students had poor language skills and found it difficult to describe situations or events.

A growing number of children had over-the-top reactions to problems in the playground or classroom, lacked manners and were unable to follow routines such as unpacking their schoolbags.

Mr Breen said a common reply to a teacher's request was "you do it". "These social issues are now impinging more on education," he said.

"And there is an expectation that schools will sort it out. These kids in later years are going to be a huge issue for society."

Mr Breen said principals had met Education Minister Peter Collier last week and appealed for more targeted early intervention, including building more school-based child and parent centres to provide health and parenting support to families from birth.

He said the 16 child and parent centres that had been funded so far were spread too thinly across hundreds of schools.

"We should have another 100 of them," Mr Breen said.

Mr Collier said the Education Department had improved the way it collected data from schools on child abuse and self-harm, which could have led to a perception that such cases had increased.

But figures from the Australian Early Development Census indicated that WA children's social competence and emotional maturity before starting full-time schooling had remained stable between 2009 and 2012.

Research had found the best way to influence children's early development was to work with their parents and carers.

"The 16 current child and parent centres will be evaluated, and the results used to steer future decisions on the program," Mr Collier said.

"The department has also entered into a partnership with Playgroup WA to forge stronger links between community-based playgroups and local schools."