The Government is considering a greater role for external advisers amid complaints that governors are failing to set rigorous targets for heads.
Schools standards minister David Miliband is now proposing more "peer review" by headteachers and greater support from councils to help governors handle appraisal.
The Department for Education and Skills wants to recruit more serving heads as external advisers.
Helen Walker of the DfES school workforce unit said: "We are looking at whether external advisers should have access to the final objectives set between governors and heads, to compare against what they advised. There needs to be a debate about how much should remain confidential."
Neil Davies, chairman of the National Governors' Council, said: "I can't see a benefit to an external adviser knowing the objectives because the job is to assess performance against the previous set."