The Acambay Graben is a major intra-arc basin of the Trans-Mexican Volcanic Belt. Trenching studies at four sites along the Acambay-Tixmadej¿ fault reveal evidence for the 1912 Acambay earthquake and at least four late Pleistocene and Holocene ground-rupturing earthquakes with similar displacements to the 1912 event. Evidence for multiple events was recognized by a combination of upward terminating faults, fissure fills, erosionally truncated fissures, colluvial wedge fills, and downward increasing separation of stratigraphic units. Sites along the central part of the ESE-WNW trending rangefront fault indicates large dip slip separations across a multi event scarp in Holocene colluvium with a penultimate event that occurred since ~5230 calibrated years before present (cal. yr B.P.). On the Huapango Plain, near the eastern end of the 1912 rupture where slip was oblique, the penultimate earthquake occurred after ~4700 cal. yr B.P., and there is evidence for at least four more earthquakes in the last ~34,000 cal. yr B.P. Three-dimensional excavation of lacustrine and channel deposits at Las Lomas yields a left-normal slip vector of S40¿5 ¿E with 105¿10 cm of slip for the last three events there. This slip vector is consistent with NNE-oriented extension across the graben. The amount and style of slip documented for prehistoric ruptures are also consistent with the 1912 rupture, with a mean of ~60 cm/event of dip slip on the rangefront and a mean of ~35 cm/event of oblique slip on the N48 ¿W trending Huapango Plain. Assuming these values represent a characteristic behavior yields an average recurrence interval of ~3600 years for the last four large earthquakes (since ~11,570 cal. yr B.P.), and a slip rate of ~0.17 mm/yr across the rangefront. Empirical earthquake parameters calculated from our paleoseismic data support instrumental measures indicating that the 1912 Acambay earthquake was of M 6.8--7.0. The 1912 event is representative of ground-rupturing earthquakes on the Acambay-Tixmadej¿ fault and demonstrates that large seismic events (M~7) can be generated by faults in the Trans-Mexican Volcanic Belt and in other intra-arc settings. ¿ 2000 American Geophysical Union