The three were arrested last June, the Canadian Broadcasting Corp. reported. In his opening statement Monday in an Ottawa court, the prosecutor said a fourth girl will be tried separately.
The teens allegedly invited other girls to an overnight party at one of their homes, gave them drugs and liquor and sent them in taxis to meet men who had paid for sex with them, the prosecutor said. The evidence is expected to include Facebook postings and tweets aimed at recruiting teens.
Investigators said they believe the teens acted on their own with no adults involved.
The non-jury trial is expected to take about four weeks.