If You Knew Suzi... is the sixth regular studio album by Suzi Quatro, released at the end of 1978, with a 1979 copyright date. By August 2012 this was still Quatro's highest-charting album in the United States (it peaked at number 37 on The Billboard 200). The album also yielded Quatro's biggest US single hit, a duet with Chris Norman named "Stumblin' In" (which reached number 4 in both The Billboard Hot 100 and the Billboard Adult Contemporary charts.