"Too Much Heaven" is a song by the Bee Gees, which was the band's contribution to the "Music for UNICEF" fund. They performed it at the Music for UNICEF Concert on 9 January 1979. The song later found its way to the group's thirteenth original album, Spirits Having Flown. It hit No. 1 in both the United States and Canada. It also rose to the top three in the United Kingdom. In the US, it would become the fourth of six consecutive No. 1s, tying the record set by the Beatles for most consecutive No. 1 songs.

Robin Gibb reportedly said on the Bee Gees' interview for Billboard in 2001 that this track was one of his favorite songs of the Bee Gees.

Barry Gibb, Robin Gibb and Maurice Gibb wrote this track with "Tragedy" in an afternoon off from the making the Sgt. Pepper's Lonely Hearts Club Band movie; that same evening, the Gibbs wrote "Shadow Dancing" for Andy Gibb (but that song was later credited to all four Gibbs)

The recording process was the longest of all the tracks on Spirits Having Flown as there are nine layers of three-part harmony, creating 27 voices, though the high falsetto voices are the most pronounced in the final mix:

Imbued with their falsetto style, it is also notable for being one of two songs on the album featuring the Chicago horn section (James Pankow, Walt Parazaider and Lee Loughnane); the other track that features the Chicago members is "Search, Find", in return for the brothers' appearance on the Chicago song "Little Miss Lovin'". On its demo version, Barry begins with count-in. This track does have some backing vocals. The demo lacks the full orchestral feel of the final song.

...
Wikipedia