Already nearing the featherweight maximum after his loss of the title to George Dixon, Erne began fighting in the lightweight division, meeting George "Kid" Lavigne for his first Lightweight Title bout on September 28, 1898 in Brooklyn.
 The twenty round draw would not determine a new champion.

In one of the most important bouts of his career, he took the world lightweight title from Kid Lavigne on July 3, 1899 in a twenty round points decision before an enthusiastic home crowd in Buffalo.
Looking back on Erne's critical win twenty years earlier, the St. Petersburg Times noted that Erne was more known for his speed and scientific skills than power, recalling that Lavigne had lost the title to "lighthitting Frank Erne."
This description of Erne was more accurate when he faced his most gifted opponents.

In a fight that some historians consider a greater show of skill than his two championship title wins, he successfully defended the lightweight title at New York's Broadway Athletic Club in a close bout against the incomparable lightweight Joe Gans on March 23, 1900.
 According to BoxRec, Gans had asked the fight to be stopped in the ninth round after being injured by an accidental headbutt from Erne.
Other sources wrote that Erne had held a decisive edge in the bout, and continuously battered Gans in the face, before Gans finally ended the fight fearing permanent damage to his eye.
 No headbutt was mentioned in their account.

On July 16, 1900, Erne faced lightweight legend Terry McGovern in Madison Square Garden in New York.
Erne had superior reach and height over McGovern, but according to most boxing writers, had not demonstrated the ability to consistently connect with the power of McGovern.
 Erne's ring generalship with his best opponents, was a slow, and deliberate strategy which took longer to end a fight.
 As the Bridgeport Herald wrote before the fight, "Erne's fights have been longer than Terry's as his record shows.
He is not the finisher that Terry is.
He is a point decision fighter more properly speaking and McGovern is a knockerout."
Though putting McGovern down in the first round, Erne was down three times in the third before his cornermen ended the fight.
Already nearing the featherweight maximum after his loss of the title to George Dixon, Erne began fighting in the lightweight division, meeting George "Kid" Lavigne for his first Lightweight Title bout on September 28, 1898 in Brooklyn.  The twenty round draw would not determine a new champion.
In one of the most important bouts of his career, he took the world lightweight title from Kid Lavigne on July 3, 1899 in a twenty round points decision before an enthusiastic home crowd in Buffalo. Looking back on Erne's critical win twenty years earlier, the St. Petersburg Times noted that Erne was more known for his speed and scientific skills than power, recalling that Lavigne had lost the title to "lighthitting Frank Erne." This description of Erne was more accurate when he faced his most gifted opponents.
In a fight that some historians consider a greater show of skill than his two championship title wins, he successfully defended the lightweight title at New York's Broadway Athletic Club in a close bout against the incomparable lightweight Joe Gans on March 23, 1900.  According to BoxRec, Gans had asked the fight to be stopped in the ninth round after being injured by an accidental headbutt from Erne. Other sources wrote that Erne had held a decisive edge in the bout, and continuously battered Gans in the face, before Gans finally ended the fight fearing permanent damage to his eye.  No headbutt was mentioned in their account.
On July 16, 1900, Erne faced lightweight legend Terry McGovern in Madison Square Garden in New York. Erne had superior reach and height over McGovern, but according to most boxing writers, had not demonstrated the ability to consistently connect with the power of McGovern.  Erne's ring generalship with his best opponents, was a slow, and deliberate strategy which took longer to end a fight.  As the Bridgeport Herald wrote before the fight, "Erne's fights have been longer than Terry's as his record shows. He is not the finisher that Terry is. He is a point decision fighter more properly speaking and McGovern is a knockerout." Though putting McGovern down in the first round, Erne was down three times in the third before his cornermen ended the fight.
Frank Erne