This will be an open-label study designed to assess the safety and plasma PK of topically applied IDP-126 Gel compared to Control Gel.

To evaluate the safety and plasma pharmacokinetics (PK) of clindamycin and adapalene in IDP-126 Gel compared with that from Control Gel in subjects with moderate to severe acne vulgaris (acne) during once daily topical application of IDP-126 Gel for 28 days.

Inclusion Criteria:

1. Male or female, at least 9 years of age (at least 12 years of age for Control Gel);
2. Verbal and signed written informed consent must be obtained. Subjects less than age of consent must sign an assent for the study and a parent or a legal guardian must sign the informed consent (if subject reaches age of consent during the study they should be re-consented at the next study visit);
3. Subject must have a score of 3 (moderate) or 4 (severe) on the Evaluator's Global Severity assessment at the screening and baseline visit

Exclusion Criteria:

1. Use of an investigational drug or device within 30 days of enrollment or participation in a research study concurrent with this study;
2. Any dermatological conditions on the face that could interfere with clinical evaluations such as acne conglobata, acne fulminans, secondary acne, perioral dermatitis, clinically significant rosacea, gramnegative folliculitis, dermatitis, eczema;
3. Any underlying disease(s) or some other dermatological condition of the face that requires the use of interfering topical or systemic therapy or makes evaluations and lesion count inconclusive;
4. Subjects with a facial beard or mustache that could interfere with the study assessments;
5. Subjects with more than two (2) facial nodules;
6. Evidence or history of cosmetic-related acne