Lord of the Flies deals with maturity and loss of innocence. Discuss what Jack learns as he comes of age.

Lord of the Flies is a bildungsroman, a coming-of-age story, in which a character, as your question states, must lose his/her innocence and grow in maturity.  Examining the characteristics and their presence in the novel through Jack's character can help define what Jack learns along the way.

First, the character must be without a father-figure.  This lack of parental structure mirrors a loss of faith in the value system the character has been raised to...

Lord of the Flies is a bildungsroman, a coming-of-age story, in which a character, as your question states, must lose his/her innocence and grow in maturity.  Examining the characteristics and their presence in the novel through Jack's character can help define what Jack learns along the way.

First, the character must be without a father-figure.  This lack of parental structure mirrors a loss of faith in the value system the character has been raised to trust.  Jack is not literally fatherless; yet while he is on the island, he is without an adult male figure to guide him.  This forces Jack to look within himself and rely on the principles he has been taught thus far to determine his course of action.  Jack struggles with the morality of taking a life when he first assumes the role of hunter; but he soon abandons those ideals in the struggle for survival and power, believing that the payoff for violating the morals outweighs the benefits of holding on to them.  By providing food, he can construct himself as the provider for the tribe and establish control over the boys.  He learns that his prior value system is of little use in his current environment.

Second, a bildungsroman involves a quest that takes the character away from civilization.  This one is obvious, isn't it?  Through his time on the island, Jack learns he is able to survive, but at the expense of his civilized nature.

Next, any quest must have obstacles, and the obstacle is most often found within the character himself.  This is true for Jack.  He battles his own conscience; he struggles between, according to Freud, his id and his superego.  And his id--his impulsive, needs-driven self--wins out when he begins to paint his face.  He learns that he can hide his true self behind another identity to excuse his immoral behavior.

Finally, the character has an epiphany, often amidst an ambiguous ending.  When the Navy officer appears at the end of the novel, Jack is confronted with his outrageous behavior.  The reader has to decide what the future holds for Jack:  Will he repent from his vile behavior, or has he crossed a point of no return?