Responses of teenagers and their parents to California's graduated licensing system.

In 1998, California adopted a strong graduated licensing system that lengthened the learner's permit stage from 1 month to a mandatory 6 months and introduced passenger and nighttime restrictions for initial license holders. The passenger restriction (no passengers younger than 20 for the first 6 months) is stronger than such restrictions in any other state; the nighttime ban is relatively weak, not beginning until midnight. Surveys were undertaken to learn what teenagers and their parents thought about the new requirements and how they responded to them.