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:
The Age of Innocence (1920) is a novel by Edith Wharton, which won the 1921 Pulitzer Prize. The story is set in upper class New York City in the 1870s.
The Age of Innocence centers on one society couple's impending marriage and the introduction of a scandalous woman whose presence threatens their happiness.