Sylvia Plath’s novel, The Bell Jar, has been the focus of much attention since it was published. Most critics have analyzed this novel through the lens of psychoanalysis and feminism. The aim of this thesis is to study it in the light of William Blake’s theory of character development which is based on the three stages of being: innocence, experience, and organized innocence. The focus of this thesis is on the effects of the collision of the worlds of innocence and experience on the character development of Esther, the protagonist of The Bell Jar. It also aims to clarify whether Esther reaches the Blakean stage of organized innocence or not. Through analyzing critical elements such as the role of imagination, social expectations, retreat from experience, embracing passion, and passivity vs. activeness in the character development of Esther, it is concluded that despite the overwhelming struggle that the world of experience puts her through, she manages to pass the second stage of experience and step into the third ideal Blakean stage, that of the organized innocence.