||Numerous sexual activities are depicted in the film, but not excessive.
Explicit images of sexual activity are also featured, but justified by context.
As the film revolves around the young female protagonist's sexual experimentation and her quest for self-identity, it is replete with verbal sexual references and sexual scenes.
Some of the stronger scenes include one where the female protagonist engages in foreplay with her mother's boyfriend and her female best friend, with shots of the trio kissing and the female protagonist touching her friend's bare breast; several sexual scenes between the protagonist and different male characters where nudity and sexual movements are depicted clearly and a scene where she and her best friend perform oral sex on two men in a toilet.
In addition, the film contains a subplot about the protagonists attraction to a woman.
In one scene, the two women are seen in bed with one implied to be performing oral sex on the other.
The female protagonist is also an aspiring comic artist and her illustrations are seen intermittently throughout the film, with animated sequences of her imaging herself as a comic character. These illustrations are often sexually-suggestive and feature nudity, particularly of the male genitalia.
||Drug taking sequences are depicted in the film but instructive details of illegal drug use are not. The film does not promote or encourage drug and substance abuse as a whole.
The film contains frequent scenes of drug use with scenes of the main characters consuming various kinds of drugs, including cannabis cigarettes, cocaine and/or acid.
||Set in the 1970's in San Francisco, 'The Diary of a Teenage Girl' is a coming-of-age drama about a young woman's search for her own identity and sexual awakening which is facilitated, in part, by her affair with her mother's boyfriend.