Surveillance video caught an image of the suspect's car driving in the area.
Investigators say the suspect pulled up next to a student in a black two-door convertible as she was walking home from school. He started talking to her from his car and then exposed himself to her.
The suspect is described as a 20 to 30-year-old man with short dark hair.
Anyone with information or who believes they have been a victim is urged to call Costa Mesa police at (714)754-5051.