Northern México (Durango, Chihuahua): Two weeks (29 July–15 August, 2005), funded by the NSF REVSYS project. This expedition was undertaken by two teams. Dr W. David Sissom (West Texas A&M University), co-PI of the REVSYS Vaejovidae project, travelled south from Texas, accompanied by former graduate students, Kari McWest and Chad Lee, and an undergraduate student, Lee Jarvis. REVSYS collaborator, Dr. Oscar Francke travelled north from MéxicoCity with Cesar Duran (former graduate student, IBUNAM), Hector Montaño (undergraduate student at UNAM), and Jesus Ballesteros (undergraduate student, Instituto Politecnico Nacional). The two teams met in Chihuahua City and spent the next two weeks traversing mountains and deserts in the northern Mexican states of Durango and Chihuahua. Vaejovid scorpions are diverse in the region and greatly outnumbered buthids and diplocentrids. Among the interesting material obtained for the REVSYS project are species of Paruroctonus, Pseudouroctonus, and Serradigitus, as well as members of the eusthenura, mexicanus, and punctipalpi groups of Vaejovis. Several potential new species await further study.