The origin, historical trajectory, and present status of the insect collection of the University of Puerto Rico at Mayagüez (collection coden: UPRM) are reviewed. The collection initiated in the mid 1920s and has grown relatively continuously thanks to efforts by several outstanding entomologists working at UPRM. As of 2007, the collection includes more than 130,000 objects (individual specimens, slides, or vials) pertaining to 25 hexapod orders. The numbers of collection objects per order are listed. The geographic emphasis is on Puerto Rico and surrounding islands. The auchenorrhynchous Hemiptera, Collembola, and Coleoptera are particularly well represented. The collection is in a process of reorganization and is available for specimen loans and related collaborative activities.