Following the formation of the Club in 1972, the club has competed in both the Sydney and Illawarra competitions.
Over the years, the Quins have had an enormous level of success both on and off the rugby field and also had many disappointments. 1974 was the first success as 2nd Grade won the Illawarra Premiership. In 1977 the Harlequins had all 4 teams in the Sydney Sub-District Grand Finals at the old Sydney Sports Ground. We won 1st grade and 4th grade. In the 1980's we were runners up in lst grade 3rd Division, but Club Champions.
The move back to Illawarra in the 1990's however witnessed the most successful era of the Quins. Starting in 1991 with the Under 19 premiership, the Club had teams in the Final series in each grade in every year until 1999. Winners in Under 19's, 2nd and 3rds at various times, culminated in winning the Club Championship and 1st grade in 1997. The success continued into the millennium again winning 1st Grade in 2001.
Sydney Suburban Rugby beckoned and during those early 2000's the Quins again excelled. The Quins were now fielding 5 grades of senior teams and a Colts team. Initially in 2nd Division, the Club were Club Champions in 2005 and Minor Premiers in the same year. The Quins were voted the "best NSW Suburban Club" in 2003.
Several factors lead to the Club declining in overall strength during the ensuing years of the early 2000's. Back to Illawarra in 2015 and the Club continues to go from strength to strength into its 50th year.