I second Rabbit, Run and I nominate The Country Girls by Edna O'Brien. For its frankness with social and sexual issues, Ireland banned it, O'Brien's parents were shamed and the family's parish priest publicly burned copies of the novel.
From Goodreads:
Meet Kate and Baba, two young Irish country girls who have spent their childhood together. As they leave the safety of their convent school in search of life and love in the big city, they struggle to maintain their somewhat tumultuous relationship. Kate, dreamy and romantic, yearns for true love, while Baba just wants to experience the life of a single girl. Although they set out to conquer the world together, as their lives take unexpected turns, Kate and Baba must ultimately learn to find their own way.
"It's a difficult trip, this coming of age . . . O'Brien tells it with love and outrage, compassion and contempt." (Los Angeles Times Book Review)
"A treasure . . . powerful . . . intelligent . . . ironic." (The New York Times Book Review)
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