Plans to change the way parents become involved in the running of Scotland's schools should be piloted first to see if they work, the Tories have said.
School boards would be replaced by more informal forums
The Scottish Schools (Parental Involvement) Bill would enable new parent councils to be established, with a wider focus than school boards.
The Scottish Tories warned that parents could lose their say over issues such as senior teaching staff appointments.
The Scottish Executive said the aim was to give parents more say, not less.
A spokeswoman said the executive was currently consulting on plans to boost parents' involvement in appointing senior teaching staff.
Scottish Conservative education spokesman James Douglas-Hamilton said he feared the bill would award local authorities carte blanche to parachute head teachers in and out of failing schools "on a whim" without fully consulting parents.
"Local authorities want to have the power to deploy head teachers as and when they want, with only lip service paid to the views of parents," he said.
"What is the point of parent councils having all these functions to help deliver education in schools if decisions concerning head teachers are taken away from them?
"If this bill were to proceed then it might be better piloting it in a couple of local authority areas. That would be the best way to gather evidence as to whether the executive's plans really do improve the workings of our schools."
The new bill, which has been backed by the Convention of Scottish Local Authorities, would give parents in Scotland powers to ask inspectors to intervene if their children's schools do not respond adequately to their complaints.
It also places a duty on every head teacher to provide a report at least once a year to parents on how a school is performing.
But the Scottish School Boards Association (SSBA) has voiced fears that the new parent councils would be "toothless" as they would lack statutory duties.
The executive said it was introducing the reforms after independent research found that 69% of parents had no involvement with their children's school even though many wanted to get involved.