The investigators will randomly assign participants with social anxiety disorder to receive oral cannabidiol (CBD) or placebo. Participants will undergo a fear conditioning and extinction trial, and the investigators will examine whether CBD increases the degree of fear reduction during extinction.

This will be a double-blind, randomized controlled trial of cannabidiol (CBD) vs. placebo for potentiating fear extinction in adult outpatients with social anxiety disorder (SAD). After providing written informed consent and passing medical screening, participants will be assessed for SAD and other mental health concerns. They will then engage in a fear conditioning paradigm in which an electrical stimulation is applied to the wrist that is aversive but not painful (at a level determined by each participant) paired with pictures of angry faces. Following the fear conditioning paradigm, they will receive orally administered CBD or placebo. They will then undergo a fear extinction phase in which the conditioned angry faces are shown repeatedly with no further electrical stimulus. Fear toward the conditioned faces following extinction will be measured using galvanic skin response (GSR) and a visual analog scale of self-reported fear. The investigators predict that CBD, compared to placebo, will result in lower GSR and self-reported fear ratings.

Inclusion Criteria:

1. Age 18 and above
2. Any gender
3. Any race/ethnicity
4. Primary diagnosis of SAD according to the DIAMOND
5. At least moderate severity of SAD as evidenced by a DIAMOND severity rating of 4 (moderate) or higher
6. Able to speak, read and write English (this is necessary because the study measures are only validated in English)
7. Concurrent medications will be allowed so long as there is not a substantial risk of interaction with CBD
8. Able/willing to consent to participate in study

Exclusion Criteria:

1. <18 years old
2. Active substance use disorder or mania according to the DIAMOND
3. Severe risk of suicide or non-suicidal self-injury in the interviewer's judgment
4. Current or past schizophrenia spectrum disorder according to the DIAMOND
5. Developmental disability, including autism spectrum disorder, according to clinical interview
6. History of organic brain illness or head injury with loss of consciousness > 5 minutes
7. Liver function abnormalities as detected by liver functioning test
8. History of allergic reaction to CBD according to clinical interview
9. Unable or unwilling to abstain from CBD or tetrahydrocannabinol use for 24 hr prior to study participation
10. Pregnancy or lack of adequate contraception
11. Any clinical factors that would preclude the participant from providing informed consent or otherwise participating in the research, according to the interviewer's judgment

Capsules will be in opaque bottles and the experimenter will not see the contents of the bottle.