Like the pre-Crisis version, this Kara claims to be the daughter of Superman's uncle Zor-El and his wife Alura. The new Kara is actually older than Superman; she was a teenager when he was a baby. When Krypton exploded, she was sent in a rocket (in suspended animation) to find and look after Superman. However, her rocket got caught in a huge chunk of the planet and she arrived on Earth years after her cousin did. Meanwhile, she was put in suspended animation, so while chronologically born before Kal-El, she is still the age of a teenager. Her arrival is discovered by Batman, who initially doubted that she was really Kryptonian, thinking that it was too much of a coincidence. Not to mention he couldn't understand a thing that she said because she only spoke in Kryptonion. Kara is scared being on a unfamiliar world, and unable to understand English, not knowing about the powers she gets from being on Earth does some damage. Batman subdues her using kryptonite and brings her to the batcave to conduct more research on her but she soon awakens and attempts to fly off, but is prevented from doing so by Superman. Discovered by her cousin she spends a long time at the Fortress of Solitude catching up on all the time she has missed and learning about Earth and its past. She is astonishingly able to learn all of Earths languages in just three months. During her stay at the fortress Kara does not get along with Krypto, Superman's dog, which makes Batman suspicious of her.
She becomes restless and pleads to go out into the world, and Superman finally allows her to as long as she stays under his supervision. In her first trip to the outside world Kara and Clark go to Metropolis, where Kara learns how Clark is able to keep his identity a secret. The Amazons learn of her existence, however, and Wonder Woman (aided by Artemis and Harbinger), comes to take Kara back to their island to be properly trained in combat by Wonder Woman and Artemis. Superman is reluctant to let her go, but grudgingly concedes, seeing it would benefit her and she would be safe. Unfortunately she doesn't stay safe. She is captured by Darkseid, and after being brainwashed, attacked her own cousin.
Superman defeats her and returns her to Earth, where he fakes her death so Darkseid will not come looking for her. She then assumes the role of Supergirl. But she feels out of place, not sure where she really belongs. At the start of Kara's career as Supergirl she joins the Justice Society in a fight with Grundy but actually just watches from a distance as she talks to Star Girl who assures her they can handle it. During the battle Power Girl arrives to help the Justice Society but finds herself loosing Kara to him much to her surprise which leads Kara to save her. Kara is unable to associate closely with Power Girl because their powers go out of control when they touch each other. Kara has also been feeling out of place because she does not know where she should belong. Because of this she finds most solace with the Amazons on Themyscira. She finds kindred spirits in her other "cousina" Superboy, Wonder Girl, and Starfire.