Ian Valentine, head of Cleveden secondary in Glasgow and president of the secondary heads in the city, said security did not come from buildings or technology but from people.
Mr Valentine told the conference, organised by Glasgow City Council and Infolog Training, that the Dunblane tragedy was caused by an adult coming into school intending to harm people. "That remains very, very unusual. There are other dangers posed by adults. Sometimes parents come into school and get upset and irate.
"What we should remember is that the greatest danger to the children is posed by other children or at least by other young people. In inner-city areas, it's almost a daily occurrence that people hang around schools where they are not pupils".
Mr Valentine warned against the danger of creating fortresses: "For some of the children at my school, it's the nicest place in their lives".
Gordon Jeyes, director of education in Stirling, which includes Dunblane, agreed and argued for each local authority to have a "safety strategy" for its schools in the widest sense of promoting pupils' welfare and security. "We need to say that the debate is not about secure systems to exclude people but to include them. That's the lesson of Dunblane".
Meanwhile, in Fife's review of school safety procedures, all school staff will be required to wear badges and visitors to sign in and out.