The central themes of Caramelo are culture and family.
The symbol that the story revolves around is a striped ("caramelo") Mexican shawl known as a rebozo. The rebozo represents several generations of families, all stitched together to create one heritage. This Latino heritage is celebrated by the author, Sandra Cisneros, as she creates a main character who identifies strongly with this culture, and whose life is changed because of it.
The theme of family is perhaps even more important to the novel, as everything that happens revolves around what it means to be a family: no matter how dramatic and painful that experience may be. Celaya, the protagonist and narrator, must tell, not just her own story of how she relates to each of her very different family members, but also her "Awful Grandmother's" story. This story is full of abandonment, pain, and treachery, and at the end of the day, Celaya and her family have to decide how to accept the fact that the people in their family have hurt them, and how to move on and accept them as a part of their lives anyway.
The most prominent theme in Caramelo is the exploration of family relationships and the merit of a dysfunctional family in regard to building a culture. The characters are typically defined by their unsavory actions, and much of the plot revolves around learning why the family members in particular are the way that they are. Many of the more "awful" characters in the family have stories that are filled with heartbreak and pain.
A central symbol of the story is the striped rebozo, and in the end, Celaya relates it to a single culture and heritage that is built from family. She decides that it does indeed carry value and beauty even if the ties that bind it, such as painful familial relationships, can sometimes be ugly.