Research I university was a category that the Carnegie Classification of Institutions of Higher Education previously used to indicate universities in the United States that engage in extensive research activity.
The 1994 edition of the Carnegie Classification defined Research I universities as those that:
The Carnegie Foundation reported that 59 institutions met these criteria in 1994.
In their interim 2000 edition of the classification, the Carnegie Foundation renamed the category to Doctoral/research universities-extensive to "...avoid the inference that the categories signify quality differences." The Foundation replaced their single classification system with a multiple classification system in their 2005 comprehensive overhaul of the classification framework so that the term "Research I university" was no longer valid, though many universities continued to use it. In 2015, the Carnegie Classification System reinstated the "Research I university" designations along with "Research II" and "Research III."