Songfacts®:

• This song was written by Fleetwood Mac's keyboard player Christine McVie, who also sang lead on the track. It finds her topsy turvy over a guy whose mood shifts with the weather. She knows he's not good for her, but her brain doesn't get to make the call (thus "over her head") - her heart does, and she's sticking with him because it sure feels nice.
  
  She was married to her bandmade John McVie at the time, but she never gave any indication that the song was about him. Unlike Stevie Nicks, Christine's songs about the vagaries of love were rarely inspired by her own relationships. She was more of a universalist songwriter who could tell relatable stories over irresistible melodies.
• This was the first Fleetwood Mac song to crack the Top 40 in America. The band had been around since 1967 and released 10 albums, but much of their output was rooted in blues without much pop appeal. That changed when Lindsey Buckingham and Stevie Nicks joined in 1975 for their self-titled album, released that July. "Over My Head" was released as the first single in America that September and made its way to #20 in January 1976, ushering in a string of hits. "Rhiannon" and "Say You Love Me" followed from the album, then came the Rumours album, which everyone seemed to own. Hits from that one include "Go Your Own Way," "Dreams," and "You Make Loving Fun."
• The single version was reworked to tighten it up and give it more pop appeal. On the album, the song runs 3:38 with an intro that slowly builds from silence; the single is cut to 3:10 with punchy percussion right off the top.
• Christine McVie wrote the song in the Malibu apartment she shared with John that looked over the Pacific Ocean. With Buckingham and Nicks new to the band, the infighting and competition that would soon plague them wasn't yet present. It was a time when McVie would write a song in her apartment and the band would record it without much drama.
• As Americans got used to hearing Fleetwood Mac on the radio in 1976, they started buying up copies of the Fleetwood Mac album. It very slowly climbed to #1, hitting the top spot in September, 14 months after it was released. This set a record for slowest climb to the top.