It happened just before 6 a.m. Wednesday in the 2600 block of Grafton Avenue in Dallas.
The mother, who wants to be called Janet, says a man walked up to her front porch and grabbed her purse. As she fought to hang on to it, her daughter, Alejandra, jumped in to help.
Alejandra says she was dragged about 40 yards, clinging to her mother's purse, before the man slapped her, knocked her to the ground and took off with the purse.
Alejandra was not seriously injured, and sustained just a few scratches and bruises. But even after being knocked to the ground, she still got up and followed him to his car, and got a partial license plate number.
Janet's other daughter, who is 14, witnessed the incident and says she froze and started screaming.
Police have not said if they have any solid leads in the case.
Police say it's never a good idea to fight with someone if you're being robbed, and they say if you see someone suspicious, the best thing you can do is call 911.
The suspect was seen driving a gray SUV.