Analysis of Adherence in Subjects Undergoing Differin Gel, 0.1% Treatment of Moderate to Severe Acne Vulgaris

All Subjects will treat the face once daily in the evening.

This group will be asked to return to the study center on weeks 1, 2, 4 and 8 for office visits (to remind the Subject to apply the study medication); in addition to the study visits on Weeks 6 and 12.

This group will receive a daily electronic reminder by email, text pager, or phone message (approximately at the same time each day) to use the study medication within a 4-hour window after the reminder and will return to the study center for study visits on Weeks 6 and 12.

In this group parents will be prompted by a daily electronic message by email, text pager, or phone message (approximately at the same time each day) to remind the Subject to use the study medication within a 4-hour window after the reminder. Parents will be instructed to then verbally deliver the message to the study Subject. Subjects will return to the study center for study visits on Weeks 6 and 12.

"This group is considered to be the standard of care arm and will return to the study center for study visits on Weeks 6 and 12. This group will not receive any kind of reminders other than the instructions provided by the study staff during the study visits."