More than 800 California school districts are offering transitional kindergarten for the first time.
The program offers age appropriate curriculum for children who don't meet the age requirements to attend traditional kindergarten.
Senator Joe Simitian wrote the law creating the grade level. He says beginning school at an older age improves a child's social and academic development.
SIMITIAN: "We're going to see fewer kids who are held back. We're going to see fewer kids who were unnecessarily placed in special education. We're going to see fewer kids who need remedial help, and we're going to see better test scores and other improvements by other measures of performance."
Previously California was one of just four states that let children start school as long as they were five years old by December 2nd of the school year. The new cutoff date is September 1st.
Simitian says transitional kindergarten comes at no additional cost to the state.