Click here to see the Hunter Libraries record for our online edition of The Age of Innocence. Click where it says "View online : access limited to Hunter College."
You may not want to read the novel online, but the ebook allows you to search the full text (see the "search within book" search box), which can be very helpful when analyzing the text for your paper.
This Oxford University Press edition also includes explanatory notes on the text.
There is also a publicly accessibly, searchable electronic version at Project Gutenberg.