This edition is written in English. However, there is a running Spanish thesaurus at the bottom of each page for the more difficult English words highlighted in the text.

From Wikipedia:

This Side of Paradise is the debut novel of F. Scott Fitzgerald. Published in 1920, and taking its title from a line of the Rupert Brooke poem Tiare Tahiti, the book examines the lives and morality of post-World War I youth. Its protagonist, Amory Blaine, is an attractive Princeton University student who dabbles in literature and has the book's theme of love warped by greed and status-seeking.