The New Mestiza

Any edition of this book is fine, but the 2nd edition has an excellent introduction by the Chicana scholar Sonia Saldivar-Hull that explains some of the strategies Gloria Anzaldua uses in this book, especially regarding the langauage (code-switching).
The third edition has a number of tributes to Anzaldua who died in 2004.
Borderlands/La Frontera: The New Mestizaa is a groundbreaking work that combines queer theory, socioogy, literature, cultural studies, and history with an autobiographical narrative about Anzaldua's life.
I didn't like it the first time I read it, but it has grown on me. Unfortunately, this is often the only book that grad students in English, American Studies, Ethnic Studies, Queer Studies are exposed to from a Chicana/o perspective. Anzaldaua's work should still be read, but it is not the only work of this type worth reading.
Czar