Season 1

The First Season of Phineas and Ferb was composed of 26 episodes (5 two-part and 42 individual episodes). It shows that Phineas and Ferb during their summer vacation, trying to make it the best they can, as Candace tries to "bust" them for it and Perry the Platypus fights the evil Dr. Doofenshmirtz. The season premiere was "Rollercoaster" and the season finale was "Unfair Science Fair Redux (Another Story)".

The last three episodes ("Phineas and Ferb Get Busted!", "Unfair Science Fair" and "Unfair Science Fair Redux (Another Story)") were initially shown in only a few countries outside of the United States as a Season 1 episode. For the United States, they were held for broadcast to just prior to Season 2, part of the launch of Disney XD as a replacement for the Toon Disney and Jetix channels. With the release of the second DVD and their placement in the iTunes Store catalog, they are now considered Season 1 episodes for all worldwide Disney markets. In addition, the title sequence for the three episodes is from Season 1, showing scenes at the end from the Original Pitch, lending further confirmation to their status as Season 1 episodes.