Some village schools could close under a new action plan approved by councillors in Powys on Thursday.
Campaigns across Wales have been fought to save village schools
The latest review will set out to examine the state of the buildings and those schools which are over-subscribed or have extra places.
There are some 112 primary schools in Powys, but the council will take at least two weeks to produce its list of those which might be affected. Plans to close a dozen Powys schools in 2003 were shelved after opposition.
Meanwhile other counties in Wales, including Carmarthenshire, Denbighshire, Swansea and Cardiff, have taken steps to review provision because of falling pupil numbers.
Following Thursday's meeting in Llandrindod Wells, a spokesman for Powys council said: "The review of primary school organisation policy was passed by an overwhelming majority.
"This policy will give us a strategic approach to provide primary education in Powys. The policy will lead to changes in the way primary schools in Powys are organised in the future."
Llangurig Primary School was one of those that faced closure in 2003.
Head teacher Ernie Jones, who is responsible for 18 pupils, gave his reaction to the new policy.
He said: "At least with the new policy there will be a level playing field where all schools will be judged by the same criteria.
"Three years ago the council didn't have a policy and targeted schools with low pupil numbers."
The quality of education, pupils numbers, transport and the cost of travel and buildings will all be assessed against the new policy.
Last year, a Powys Council report showed that 40 schools have 25% or more spare places. The objective is to reduce the number of empty seats to 15 schools with 15% spaces by 2007/2008.
In its first review nearly three years ago, Powys council said that small schools with less than 28 pupils were not viable, but it was eventually forced to look again at its policy.