Selected highlights from the kindergarten database:

Kindergarten entrance age

• In half of the 50 states plus the District of Columbia, students must turn age 5 by the end of September to attend kindergarten.
• Nineteen states requires students to turn age 5 on or before Sept. 1.

Kindergarten attendance requirement

• Fifteen states plus D.C. require children to attend kindergarten at age five or require kindergarten attendance prior to enrolling in first grade.
• Thirty-five states do not require kindergarten attendance.

Compulsory school age

• Most states require children to attend school by age 6 (26 states) or age 7 (14 states).
• In eight states – Arkansas, Connecticut, Delaware, Maryland, New Mexico, Oklahoma, South Carolina and Virginia – plus D.C., the compulsory school age is 5.
• Pennsylvania and Washington require children to attend school at age 8.

Source: Economic Commission of the States

Available at: http://www.ecs.org/html/educationIssues/Kindergarten/KDB_intro_SF.asp