The incident happened at around 7:30 p.m.
It involved United ExpressJet Flight 4226 headed for Nashville and Scandinavian Airlines Flight 908 headed to Oslo, Norway.
The planes were taxiing for departure when the left wing of the Scandinavian Air plane clipped the tail of the United ExpressJet.
Both planes went back to their gates. The passengers on the United flight were put on another plane and are en route for Nashville.
Scandinavian Air is making accommodations for their passengers.
No injuries were reported.
The SAS plane was an Airbus A330. The United Express plane was an Embraer 145.
ExpressJet released a statement saying:
"ExpressJet Flight 4226, operating as United Express, from Newark (EWR) to Nashville (BNA) was on the taxiway in EWR when its tail was contacted by another aircraft. All 31 passengers deplaned the aircraft normally and were bused to the terminal where they are being re-accommodated. ExpressJet is working in coordination with officials to determine the cause."