SNP members have backed a motion that would see the age children start school increased to six years old.
Toni Guigliano, the party's policy convener, also proposed introducing a "statutory play-based kindergarten stage for three to six-year-olds".
Members overwhelmingly passed the motion at the SNP conference, which will not necessarily become policy.
The Educational Institute of Scotland (EIS) said care should be exercised if the motion is implemented.
It would bring Scotland into line with countries such as Finland, where formal education starts at seven.
