The song was released on the radio stations in September 2007, with less successful than their previous single, "Luz Sin Gravedad".
To choose the fourth single, Belinda did a survey to her fans, which won "Alguien Más", followed by "Never Enough", "Amiga Soledad", "Pudo Ser Tan Fácil" and "Good... Good". Unlike the first three singles, "Alguien Más" doesn't have an English version.
The single was written by Belinda, Nacho Peregín, Kara DioGuardi and Mitch Allan, who also produced the song. The song is about a girl whose boyfriend isn't the same; she feels there is some other girl (someone else) that he is seeing and she is torn apart and won't forgive him.
According to the official Belinda's site, the artist filmed the music video in late July 2007, where she was the producer and guionist. It was to be released but the video was cancelled for unknown reasons. But even though the song was not promoted with a video, it entered the top 100 of the Mexican and Chilean Charts.