Lana Lang makes the leap from Superboy to adulthood in “The Girls in Superman’s Life”, a story written by Edmond Hamilton in Superman #78 (July 1952). Lana wants to become a journalist and heads to Metropolis where Perry White is convinced to give her a shot. Lois Lane takes her under her wing and Lana proves to be a pest to adult Superman too, inadvertently threatening to give away his secret identity. This is the first appearance of an adult Lana Lang.
Lana ends up getting hired by a rival newspaper at the end of this story.