Delegates at the Educational Institute of Scotland annual conference this week will be urged to insist that colleges are properly staffed and funded before agreeing to take on problem pupils.
This follows unrest south of the border where the National Association of Teachers in Further and Higher Education placed the issue high on its conference agenda.
In last month's Scottish elections, all parties strongly supported moves to allow pupils aged 14-plus who are turned off by the traditional academic curriculum to attend college.
The Scottish Executive's lifelong learning strategy and its response to the national education debate reinforced such plans by calling for closer collaboration between schools and colleges, including joint curriculum planning.
But Howard McKenzie, principal of Jewel and Esk Valley College, told The TES Scotland: "The Executive seems to will the ends but not the means.
Colleges are not funded to take pupils in this way."
Mr McKenzie said the 3,000 school pupils who came to his college for two to three hours at a time this session attracted the same funding as 15 students doing a full-time higher national diploma.
Along with two other east of Scotland colleges, Stevenson and West Lothian, Jewel and Esk Valley is now refusing to take any S3 pupils next session - a serious blow to the Executive's plans.
The three colleges have also been hit by trouble caused by disaffected pupils to the extent that they have drawn up a contract for schools stipulating that any pupils who step out of line will immediately be sent back, with no questions asked.
Around 30 schools in East Lothian, Midlothian and Edinburgh which send pupils to Jewel and Esk Valley have signed the contract, although Mr McKenzie admits that not all of them did so happily.
He said: "I have to support my staff and I have great sympathy with lecturers who came into FE to teach people vocational skills for work and end up with a bunch of disaffected youngsters whom the schools don't want.
I think it's appalling."
The EIS conference motion will be moved by Jim Park, a lecturer at Fife College in Kirkcaldy who is also education convener of the Green Party. Mr Park stressed that he has no objection to teaching pupils with social, emotional and behavioural difficulties.
But he has had to walk into a class of 15 such pupils without any background information and no proper training. "This is not only a disservice to lecturers but to the young people themselves."
Mr Park accuses some schools of being "less than truthful" in the information they make available about pupils. "They often describe them as having attendance problems without any reference to their social and emotional difficulties," he says.
The Executive points out that its lifelong learning strategy commits it to "develop a joint schoolsFE strategy and implementation plan, including a review of funding mechanisms". Lewis Macdonald, Deputy Minister for Lifelong Learning, reinforced the call this week for colleges and universities to widen opportunities for school pupils (page six).