Director Marielle Heller spoke with Devin Faraci of Birth. Movies. Death. about her work bringing Diary of a Teenage Girl to the screen and about the film's straightforward approach to the risky subject of a sexual relationship between a 15-year-old girl (Bel Powley) and a much older man (Alexander Skarsgård), who also happens to be the boyfriend of the girl's mother (Kristen Wiig).
Says Heller of finding Powly for that pivotal role, "'I had always felt this was going to be the most impossible role to cast because she has to be great with drama but also great with humor, she had to look like a little girl but also a woman, she had to look self-conscious and yet had to have the ultimate confidence. She had to turn on a dime and go through every possible emotion, and we had to believe she was someone who could grow up to be a comic book artist. She needed to look like all of us and yet have this strange beauty… and then Bel Powley came along, and she embodied all those contradictions."