ARTstor
Provides curated collections of art images and associated data for non-commercial and scholarly, non-profit educational use. The Charter Collection is made up of over 300,000 images.

CAMIO: Catalog of Art Museum Images Online
Offers rights-cleared, high-quality art images for class projects, art history and studio art programs, course Web sites, lectures, presentations, and research resources.

A guide to Locating & Citing Images

Also refer to the Key Websites section of this guide for image sources.