The Country Girls, both the trilogy and the novel, is often credited with breaking silence on sexual matters and social issues during a repressive period in Ireland following World War II and was adapted into a 1983 film.

Archbishop McQuaid and then Minister for Justice, Charlie Haughey decided that "the book was filth and should not be allowed inside any decent home.

This comment was frequently interpreted as referring to a formal "Kingsley Amis Award", including by O'Brien's publishers, but no such literary prize exists.

[11] The novel is an exploration of the trials and tribulations of two friends set against the backdrop of 1950s Ireland, showing the influence of James Joyce in the humane attention to detail and thought and the rather lyrical prose of the narrator Cait.

The ending, wherein Cait is deceived by Mr Gentleman, can be considered as a call by O'Brien for a reconsideration of Catholic values in Irish society.

O'Brien helped to launch a new generation of Irish writers more focused on the demands and values of society, such as Enright, Nuala O'Faolain and Colm Tóibín.