The county announced the 5 p.m.- 6 a.m. curfew on Thursday evening. The curfew is in effect Friday, Saturday and Sunday.
Teenagers who are in the area without an adult can be fined up to $1,000.
The parent or guardian responsible for the teenager can face the same fine – or worse.
The move arrives after weeks of large crowds of teenagers roaming throughout the area.
County Executive Angela Alsobrooks railed against the activity in the area a number of times – taking particular exception to parents who were reportedly renting hotel rooms for their children to party in.
Teens from throughout the DMV were reportedly using ride-share to go to National Harbor, and police were called to at least five hotel parties, despite stepping up patrols in October.