Harding has averaged 11.2 points, 4.2 assists and 3.3 rebounds during her six-year WNBA career. She played the last two seasons with Atlanta, starting 65 of 68 games. Last season, she averaged 12.3 points, a team-high 4.5 assists and shot a career-best 82 percent from the free throw line.
Sparks general manager Penny Toler says Harding will be the team's starting point guard.
Harding earned All-Star honors in 2010 with the Mystics, helping them to the Eastern Conference title. She also played two seasons with Minnesota and made the league's all-rookie team.