Undrafted during her rookie season, Hammon was signed to the WNBA on May 12, 1999 and joined the New York Liberty. She had a solid rookie season statistically, backing up starting point guard Teresa Weatherspoon. Her aggressive play at both ends of the court made her a favorite among Liberty fans. After the 2003 season, Hammon took over for Weatherspoon as the Liberty's starting point guard and, with Vickie Johnson and Crystal Robinson, became one of the team's co-captains in 2004.