Inclusion Criteria:
* 15-21 years old
* For minors, parent/legal guardian able to provide consent and child able to provide assent; for adults, ability to self-consent per MacArthur Competence Assessment Tool for Clinical Research
* Ability to comply with study procedures
* Treatment-seeking youth diagnosed with CUD as per the Mini-International Neuropsychiatric Interview (MINI-KID (Sheehan et al., 2010) for 15-17 years old and MINI (Sheehan et al., 1998) for 18-21 years old)
* Cannabis use 3+ days per week (or 12+ days in the past month) as verified by Timeline Followback (TLFB) (Sobell \& Sobell, 1996)
* Fluent in spoken English
Exclusion Criteria:
* Medical conditions contraindicated or associated with altered TMS risk profile, including history of intracranial pathology, intracranial lesions, epilepsy or seizure disorders, or individuals with a family history of epilepsy or seizure in a first degree relative, traumatic brain injury, brain tumor, stroke, neurocardiogenic syncope, mania/bipolar disorder, implanted medical devices or metallic objects in the head, current pregnancy or not using effective contraception if capable of becoming pregnant, or any other serious medical condition or contraindication as judged by the study physician; moderate to severe heart disease, pediatric populations with risk factors for neurocardiogenic syncope (history of syncope/presyncope related to noxious stimuli, anxiety, micturation, or posture)
* Inability to undergo MRI.
* Diagnosis of psychosis, cognitive disability or active suicidality. The MINI (Sheehan et al., 1998, 2010) will be used to assess current psychiatric comorbidities and the Ask Suicide-Screening Questions (ASQ) will be used to assess suicidality (Horowitz et al., 2012).
* Primary current alcohol or substance use disorder, except for caffeine or nicotine.
* Taking a medication with high seizurogenic potential (e.g., clomipramine, tricyclic antidepressants, selective serotonin reuptake inhibitors, serotonin-norepinephrine reuptake inhibitors, anti-psychotics, lithium, bupropion -e.g. Wellbutrin). Participants taking psychotropic medications will be included if dose is stable for ≥4 weeks with no anticipated changes during the study period. All concurrent treatments will be monitored during the study period.
* If an individual is currently taking antibiotics that affect the central nervous system such as Fluoroquinolones (Ciprofloxacin, Levofloxacin, Moxifloxacin) or Imipenem, medications that have the potential of lowering seizure threshold, participation in the study will be delayed until 5 days after the last antibiotic dose.
* If an individual is taking antihistamines (i.e. Benadryl/diphenhydramine), they will be asked to refrain from using the antihistamine for at least 24 hours before the TMS session. If the participant is not able to do so, they will be excluded from the study.
