When Kara Zor-El landed on the planet Earth, she met her cousin, Kal-El (more popularly known as Superman). Kara wanted to live with Kal, but her cousin couldn't risk exposing his secret identity, so he registered her at the Midvale Orphanage, explaining to the Orphanage's headmaster, Mister Dixon, that Linda's parents were killed in a natural disaster and that she was now an orphan.
Taking up the "Linda Lee" name and wearing a brown wig to hide her real identity, Kara lived under the tutelage of Headmistress Miss Heart as she trained with Superman and performed super-deeds secretly. As living there, she befriended a young orphan boy named Dick Wilson (later Malverne), and adopted a stray cat whom she named Streaky. Although people weren't rude to her, Linda felt lonely and displaced and hated the Orphanage.
Eventually, Linda was adopted by Fred and Edna Danvers and left the Orphanage shortly before Superman revealed Supergirls existence to the world,, although she would return several times to the Orphanage to do voluntary work.