Hi again Lori!
For other guests, if you click
HERE, you'll be taken to the September 2008 park calendar for the Magic Kingdom. The hours listed on the calendar are the hours that the park is open to the general public.
Disney resort guests have the added benefit of being able to participate in Extra Magic Hours. If you click on the "Extra Magic Hours" link on the September 18 box, you'll see that on that date, the Magic Kingdom has morning Extra Magic Hours. That means that Disney resort guests only can enter the park an hour earlier than everyone else. The Extra Magic time is
in addition to the hours listed on the calendar.
So, to specifically answer your question. On September 18, you can enter the park at 8:00 a.m. if you are a Disney resort guest, and at 9:00 a.m. if you are not.