Gomez began her acting career at age seven, playing Gianna on Barney & Friends. She said that she learned "everything" about how to act while on the show. Season 7 of Barney & Friends, when Selena Gomez was on the show, was held up for some time. Because of this, the episodes featuring Gomez did not air until she was in 5th grade.
This resulted in some mild controversy/confusion as to whether she was on Barney in the 5th grade or the 1st grade. She later had minor roles in Spy Kids 3-D: Game Over and the TV film Walker, Texas Ranger: Trial By Fire. In 2004, Gomez was discovered by the Disney Channel in a nation wide scouting. Gomez appeared as a guest star on The Suite Life of Zack & Cody and had a guest appearance – that later turned into a recurring role – on Hannah Montana from season's two to three. In early 2007 Gomez was cast in the Disney Channel series Wizards of Waverly Place as one of the three main characters, Alex Russo.
In 2008, Gomez appeared in Another Cinderella Story, the direct-to-DVD sequel to the 2004 Hilary Duff film, opposite Drew Seeley. She also had a minor voiceover role as one the Mayor's ninety-six daughters in Horton Hears a Who! which released in March of that year. In April, Lacey Rose, of Forbes ranked Gomez as being fifth on their "Eight Hot Kid Stars To Watch" list; and Rose described Gomez as having been "a multitalented teen". In June, 2009, Gomez appeared in the made-for-television Disney Channel movie, Princess Protection Program with her then best friend Demi Lovato. On August 28, one month after appearing in Princess Protection Program, Gomez appeared in Wizards of Waverly Place: The Movie, a made-for-television film based on the show.
In 2009, Gomez did a guest appearance as herself in one episode, of Lovato's Disney Channel television show Sonny With a Chance, entitled "Battle of The Network Stars". Gomez, along with two cast members of Wizards of Waverly Place appeared in a television three-way cross-over episode with Hannah Montana and The Suite Life on Deck, entitled Wizards on Deck with Hannah Montana. In February 2009, Gomez signed on to star as one of the two female leads in Ramona and Beezus, a film adaption of the children's novel series by Beverly Cleary. In March, 2010, Variety reported that Gomez was set to star as one of the three lead roles in Monte Carlo. (Wikipedia)