Greenewalt was born in 1871 in Beirut, then part of Syria, to Samuel Hallock and Sara Tabet. After her mother began exhibiting symptoms of mental illness, eleven-year-old Greenewalt and her siblings were sent to live with friends and relatives in the US,[3] where Greenewalt spent the remainder of her youth in the Philadelphia area. As a young adult Greenewalt studied piano at the Philadelphia Conservatory of Music and then with Theodor Leschetizky in Vienna.