Langley High School and McLean High School hold back-to-back graduations today in downtown Washington.

Here's what you need to know.

1. Both graduations are held in cavernous Constitution Hall to accommodate, moms, dads, sisters, brothers, grandparents and extended family members. Langley's begins at 10 am. McLean at 2 p.m.

2. McLean is graduating 428 seniors. Speaker: Anne Moore, Former CEO Time and one of Fortune 500 Most Powerful Women, McLean Alumnus.

Langley is graduating 500 students. Speaker: James R. Clapper, Jr.,  lieutenant general (ret.) in the United States Air Force and currently the U.S. Director of National Intelligence, which is located in McLean.

3. Weather forecast. Sunny, High in the low 80's. Perfect graduation weather.

4. All night graduation parties. Both schools hold them. See our story.