Stephanie Philips, 20, pleaded guilty on Monday to leaving the scene of an accident involving a death.
No sentencing date has been set, though she faces a mandatory one year sentence.
Philips was accused of striking 17-year-old Denise Cotteta when she walked into traffic on Germantown Pike back in March, 2010.
Cotteta was celebrating her school's basketball championship - and had been to several parties where alcohol was involved.
Authorities say that Cotteta had a small amount of alcohol in her system - but don't know why she walked into the roadway.
Blood tests reveal that Philips was not impaired before the accident.
Philips remains free on $250,000 bail.