"Rock Steady" was from the group's 1987 LP, Just Gets Better with Time. This was the Whispers eighteenth studio album, and it became the second highest charting album of their career at #22 - only the band's self-titled 1979 album charted higher, at #6.
The video is a pretty standard performance piece, although the mustaches of Wallace (Scotty) and Walter Scott are prominently featured. Sadly, "Rock Steady" was the last big hit of the Whispers' career, although they continue to record and perform to the present day.
Cool trivia fact: "Rock Steady" was co-written by L.A. Reid and Babyface, who also produced the Just Gets Better with Time album (it was one of their first projects together).