Jennifer Porter, 28, was charged with leaving the scene of a deadly accident, an offense that carries up to 15 years in prison. The dance teacher was released on $7,500 bail.
The March 31 accident killed Bryant Wilkins, 13, and Durantae Caldwell, 3. An 8-year-old sister and 2-year-old brother were injured.
In a news conference earlier this month, Porter admitted through her lawyer that she was involved in the accident. He said she was too afraid to stop. Porter also apologized to the victims' mother.
Some black leaders criticized authorities for not arresting Porter sooner, complaining that she would have been taken into custody more quickly except that she is white and the children were black.
"She's very sad," said her lawyer, Barry Cohen. "She's cooperating far more than any other defendant I've ever known."
Porter, who was suspended from her job after admitting her role in the accident, had no comment.
Sheriff's deputies said the children were crossing the street at about 7 p.m. on their way home from a community center. They were not in a crosswalk.
Investigators initially said as many as two other vehicles were involved in the hit-and-run, but later said Porter's car might have been the only one.
Cohen said Porter contacted his office the day after the accident, and he told authorities the next day she was the driver.
Pam Bondi, a spokeswoman for the prosecutor's office, said the nature of the case demanded that investigators work carefully before making an arrest.
"Traffic fatalities are always time-consuming investigations, in that you must reconstruct what happened in an accident," she said.
Sheriff Cal Henderson said his office had received calls from some people complaining that Porter was not facing more serious charges. He explained that prosecutors would have had to prove at least two violations — other than leaving the scene — to warrant a vehicular homicide charge.
"There would have to be something else involved, and it just wasn't there," Henderson said.
Porter has so far refused to talk to investigators, Henderson said.
While Porter is unlikely to get the maximum, prosecutors are expected to seek some prison time. "We view this case very seriously, and the sentencing guidelines call for a prison sentence," Bondi said.
Last week, the woman's parents, James and Lillian Porter, were questioned by authorities. Investigators said cell phone records show that Jennifer Porter called her parents' home shortly after the accident.
The couple originally refused to answer questions and were told by a judge they would be jailed if they did not cooperate. Florida law does not shield conversations between parents and children, as it does spouses.
An attorney for the children's mother, Malissa Wilkins, did not immediately return a call for comment. She had said she did not consider race an issue in the accident and was satisfied with how authorities were handling the case.