The biochronology of eight events (first or last occurrences) among species of the planktonic foraminifer Neogloboquadrina plexus have been examined in six Pliocene to Quaternary deep-sea sequences drilled during ODP Leg 167 off the coast of California. The sites form a meridional transect along the California margin from 31°N to 41°N, covering an area under the direct influence of the California Current and associated upwelling system. Using age models based on combination of calcareous nannofossil and radiolarian data and magnetostratigraphic chron boundaries, ages were assigned to the events, thus allowing investigations of their spatial and temporal distribution. Three of the events have been identified as clearly diachronous; two of these seem to represent examples of latitudinal immigrations. The evolutionary activity in the neogloboquadrinid clade on the California margin appears centered around 2.1Ma, with most of the events occurring between 2.5 and 1Ma. This interval was a time of major climate change. No events have occurred after 0.7Ma supporting the notion that the extreme climate variations of the Late Pleistocene inhibited speciation. Assignment of ages to events defining boundaries of the California margin (CM) zones of Kennett and others has enabled us to compare this zonation with the standard planktonic foraminiferal zonal schemes. Seven of the neogloboquadrinid events occurred during the last 2.5myr, suggesting that the time resolution of the CM zones (including the coiling dominance zones of Lagoe and Thompson) during this interval is at least twice that of the standard planktonic foraminiferal zonation. The remaining Pliocene is divided only into two CM zones compared to six standard planktonic foraminiferal zones. One of the Pleistocene neogloboquadrinids is formally described as a new species.