"By changing the kindergarten entry age from 5-years-old by December 2nd to 5-years-old by September 1st, the hope is to weed out 4-year-olds who typically aren't ready for school. California is one of only 4 states with a cut-off date later than December 1st.
"We have one-quarter of our school population too young, not doing well unnecessarily. It's a simple fix that impacts millions of California kids in years to come," said State Senator Joe Simitian (D) Palo Alto.
Under the proposal, roughly 100,000 California kids would have to wait another year. Research shows beginning school at an older age benefits academic performance and social development.
The state senate approved the measure, 28-4 getting bi-partisan support. All the opponents were democrats.
"As a parent, I want my children to start kindergarten early. I think, as a society, we want them to get more education, not less," said State Senator Lois Wolk (D) Davis.
And by delaying the entry age, some parents worry about the financial impact of having to pay for daycare or pre-school for another year. Still, teachers insist the move is good.
"That would definitely more beneficial to them, if they spend another year in pre-school getting those kindergarten readiness skills together," said teacher Dana Rivers.
"The class keeps moving and that child that's not ready falls behind," teacher Melissa Ali.
For quick learners, parents would still be able to ask their school districts to let their 4-year-old start kindergarten.
The proposal now heads to the assembly. If passed the new age requirement would be phased in over three years beginning in 2012.