I have a 8 hour layover at Washington Dulles Airport. Is there a place to store luggage securely while I head into D.C. for a few hours?

Call your airline and make sure your luggage will not be checked all the way through.

An eight hour layover at Dulles isn't as long as it sounds.

i am flying in on American and then switching airlines to maxjet, so no chance of them being checked through.

A lot of people seem to ask this question (myself included)
since 9-11 I don't know of any major airports that have this service..
the only thing related to this issue, that I tried--was shipping my suitcase via Fed-Ex to my hotel..
I was recovering from shoulder surgery and felt it was worth the expense...Of course I called ahead to my hotel to let them know and Fed-Ex had it there the day I specified...cost me $29...

Did you ask? I once flew from CHS to ATL only to board a charter delta flight from ATL to LAX and the gate agent was able to check my bags.

Ask.

Just don't claim your checked bags when you arrive at Dulles.

I do this all the time, including just last Friday at Midway. I went into town and came back to get them at 9pm. There's nothing I cannot replace in my luggage.