"Someday (I Will Understand)" is a single from Pop singer Britney Spears originally released from the EP/Bonus disc of Britney & Kevin: Chaotic... The DVD & More during the third quarter of 2005, though the song was later included in its Hi-Bias Signature Radio Remix form on the B in the Mix: The Remixes compilation.

"Someday" was written by Spears herself two weeks before she learned of her pregnancy with her first child, Sean Preston Federline. Spears plays all of the piano accompaniment on this record. The track was produced by Guy Sigsworth, who also produced "Everytime". The song also earned Spears an award for "Best Pop" at the Indonesia Magazine Awards.