The song was inspired by a woman approximately 18 years old named Stephanie Buffington, for whom both Lee and Love's guitarist Bryan MacLean had affections.

[2][6] AllMusic critic Matthew Greenwald has described the song as "a combination of hard, psychedelic rock with a free jazz interlude.

[11] Edna Gundersen and Ken Barnes of USA Today described the song as being "among the most attractively sophisticated of the era.

"[12] Author Domenic Priore considers it a prime example of Lee's "fiery passion" and remarks how the song "breaks into a jazzy solo without losing its rock 'n' roll grit.

[14] Authors Scott Schinder and Andy Schwartz described Cantrelli's saxophone solo as being in a similar style to John Coltrane.

[15] "Stephanie Knows Who" had been intended as a single release in late 1966, backed with "Orange Skies" and was assigned catalog number EK 45608.

[17] AllMusic critic Cub Koda describes the Move's version as "a psychedelic number with loads of wah-wah guitar from Roy Wood.