For me, nothing could be more important to my adolescent awakening than Blume's novel (this, and her equally impressive novel, Deenie).
The protagonist struggles not only with identities of faith (one parent is Christian, the other Jewish) but also with her sexual identity. While most novels of Blume's day were aimed at male maturation, Margaret proved herself to be as complex and intriguing than any of her male counterparts.
For me personally, the mysteries of menses, the enigma of sexual attraction, and the complexities of "fitting in" made the world a more navigatable planet.
Interestingly, Blume's novels, esp "Margaret" are among the most banned books of all time. It is very sad to me, and to the author, who has said,
“[I]t's not just the books under fire now that worry me. It is the books that will never be written. The books that will never be read. And all due to the fear of censorship. As always, young readers will be the real losers.” — Judy Blume