The Electoral Reform Society has hailed Scotland's council elections as a resounding success.
Tens of thousands of ballots were rejected
The organisation has suggested that there were "major inadequacies" in the vote for the Scottish Parliament, which saw more than 140,000 rejected ballots.
However, a report from the society said that the Single Transferable Vote (STV) system used in the council election worked well.
It wants Holyrood to adopt the STV method, a call backed by the Lib Dems.
Research carried out by the BBC has shown that the proportion of spoilt ballot papers was far lower for the council election on 3 May, with 38,341 local authority votes rejected.
The Electoral Reform Society has prepared an interim report on the election.
It has indicated that voters coped well with the STV system, which saw candidates listed in order of preference.
It said that most of the confusion was due to the different voting systems for parliamentary seats, and has called for STV to be adopted across the board.
Dr Ken Ritchie, the chief executive of the Electoral Reform Society, said there had been "major inadequacies" in the parliamentary vote.
"The same day, local government elections held under STV have managed to deliver decent local government to Scotland," he said.
"This was a major vote of confidence for the new system."
The Liberal Democrats have joined the call for STV voting at both parliamentary and local level.