"Since Yesterday" is a synth-pop song performed by Scottish female duo Strawberry Switchblade, the lead single from their self-titled album. It became their only major hit and it's the song the group are best remembered for.

"Since Yesterday", primarily written by Rose McDowall, was written during the early days of the band. The song was initially called "Dance" and was debuted at their live shows in 1981-82. The only recording of "Dance" that survives is of a David Jensen BBC session the band did in October 1982, when they were still unsigned. While the musical structure stayed the same, the lyrics were extensively rewritten by McDowall when the duo recorded their debut album, and was eventually retitled "Since Yesterday".

The track's opening fanfare came from the third movement of Sibelius's Symphony No. 5. The duo worked with producer David Motion and the song presented a musical change from the group, whose previous single, "Trees and Flowers", had a folk-pop sound, while "Since Yesterday" and their later album saw them embrace the synth-pop and new wave sound which was more current with the times. The single's two non-album b-sides, "By the Sea" and The Velvet Underground cover of "Sunday Morning", were, just like their first single, produced by David Balfe and retained that folk-pop sound of "Trees and Flowers", however.

After releasing their debut single, "Trees and Flowers", on an independent label, the duo were signed to Korova, a sub-label of the Warner Music Group. "Since Yesterday" was chosen as the group's debut single for the label, in October 1984. The song initially failed to become a success, entering the UK charts at #89 at the end of October. However, it slowly climbed the charts (although never breaking the top 40) until the end of the year. After the Christmas period, Warners executive Rob Dickins decided to push more aggressively the publicity machine for the single, which had by then peaked at #47, and TV adverts for the single were produced, as well as several TV and magazine appearances. The marketing push worked, and the single cracked the UK top 40 on the second week of January 1985, climbing to #5 two weeks later. The single eventually spent 20 weeks on the UK charts, about twice as many weeks a top 10 single spent in the charts at that time.

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