What kind of experience do people have to go through to "come of age" in the eyes of society? Do they have to live in poverty or lose someone important to them? Does their own mother have to love them at all? Francie, a Brooklyn girl growing up in the early 1900s goes through all of these things; This is her life, this is what made her grow up.
Francie grew up in poverty. But poverty still exists today: still, so much of the population is living in poverty and grows up in poverty. Children who grow up in conditions where everyday life can be a struggle realize how hard the world is to live in so much earlier than those of us who don't.
When Francie's father died, she was exposed to the pain of losing the one person in her family who understood her better than everyone else. Francie grew up a little more because of this, and had to deal with his death herself. Also, her family life would never be the same, because Johnny Nolan's death affected not only her but her mother and her brother as well.
One of the things that made Francie grow up as well was love. When her mother gave birth to her younger brother, Cornelius, she loved him, but did not love Francie, but instead felt pity for her, love out of guilt. When Francie confronts her mother about this, she realizes that it's true, and has to cope with that fact that her mother does not love her as she loves Cornelius.