Welsh schools planning to invite in adult learners should tighten up on child protection to prevent a Dunblane-style tragedy, says a leading expert on youth justice.
Professor Howard Williamson issued his warning as newly drawn-up guidelines on community focused schools (CFSs) advise an urgent review of safety and protection policies.
Glamorgan university's professor of European youth policy threw his support behind moves to welcome adults into schools to learn alongside children.
But he also said the Dunblane massacre, where 16 children and a teacher were shot dead, should not be air-brushed from history.
"Post-Dunblane, we had the rise of fortress schools," said Professor Williamson. "With community focused schools, we now have security versus accessibility."
New Assembly government guidance (Community focused schools: making it happen) warns schools that over-18s who attend classes with children are not required to undergo criminal checks.
It gives examples of adult learners attending French lessons and family support sessions during the day, and of volunteers helping to run out-of-hours evening clubs.
The new advice comes a year after the Association of Directors of Education in Wales and community learning charity ContinYou Cymru said every school should offer out-of-hours activities for pupils and local people.
Jane Davidson, minister for education, lifelong learning and skills, said education would be available from the cradle to the grave with the emergence of CFSs.
But Professor Williamson, speaking this week at ContinYou Cymru's second annual conference on CFSs in Llandrindod Wells, branded the minister's speech "gushing".
Delegates heard how the growth of CFSs would help raise attainment, improve attendance and behaviour, boost children's health and offer wrap-around childcare.
Schools were urged to create a friendly environment for adults, while making children feel safe.
Mike Keating, director of education in Rhondda Cynon Taf, said its plans for CFSs were making progress through schools working together in clusters.
The new guidance advises councils to use clusters, managed by the head of a lead school, as a way of sharing resources and funding. But Professor Williamson said an all-powerful head could create internal tensions, and said shared management was a better option.
Pam Boyd, chief executive of ContinYou Cymru, said she was confident every school in Wales had done something to become more community focused over the past year.
But she said: "Rural schools where children are bussed to and from will have the biggest problems - especially with transport arrangements."