[7] Not That Kind of Girl received mixed reviews but was a commercial success, reaching number two on The New York Times Best Seller list on October 19, 2014.

[9] Hadley Freeman, in a review for The Guardian, described Dunham as being a smart and talented writer, and the book as being brutally honest, but also narcissistic and thin in experience.

[10] In The New Republic, James Wolcott found the book filled with "chatty punch lines, airy anecdotage, and sour kiss-offs" and, ultimately, "callow, grating, and glibly nattering.

In her book, Dunham describes examining her sibling Cyrus's genitals when they were children out of curiosity, bribing them with candy for kisses and casually masturbating while lying in bed next to them.

"[16] Child sexual abuse expert David Finkelhor said that a judgement requires more than a single incident, and psychologist Sharon Lamb opined that the incidents described in the book were "within the norms of childhood sexual behavior" and that "It wouldn’t be sex offender wrong, it would be inappropriate..."[19] Dunham later apologized for some of the wording in the book, specifically the joking use of the term 'sexual predator', which she described as insensitive.