Does Osan have a preschool for 4 year olds or is it just daycare at the CDC?

The Osan Services page has the information you're looking for. I've been here for almost a year and my 3, soon to be 4 year old is still on the waiting list for the enrichment program.
http://51services.com/cdc.html

http://51services.com/sap.html This is the link for the School Age Program for kids 5 - 12...just in case.

Don't forget - you can always send your kids to a Korean pre-school program. They are very reasonably priced (by American standards) and it's a great way for your kids to learn about another culture.

Way back when, we sent our kids to a Korean pre-school that operated at a church. It was a great experience for them.

It seems like it would be difficult for them because of the language barrier. But with little kids - that disappears in no time.

Depending on your familial rank and the child's birth date OAES has Sure Start. There is also a part day enrichment program.

Osan has an absolutely excellent preschool program. My 4-old attend very day from 8:30-11:30. The teacher is superb and the classroom is a very caring place. I was nervous about sending him every day, but he gets up ready to go. The program is called "Part Day Enrichment". I recommend it HIGHLY.