Although parietal cortex has been implicated in the neural processes underlying visual attention, the nature of its contribution is not well understood. We tracked attention in the monkey and correlated the activity of neurons in the lateral intraparietal area (LIP) with the monkey�s attentional performance, using contrast sensitivity of a go-nogo probe as the assay for visual attention. The ensemble activity in LIP across the entire visual field describes the spatial and temporal dynamics of a monkey�s attention. Activity subtending a single location in the visual field describes the attentional priority at that area, but does not predict that the monkey will actually attend to or make an eye movement to that location. Activity in LIP before the probe appears determines how the monkey will respond to it, but the response to the probe itself does not. LIP neurons respond more to a probe that cancels a saccade plan than one that confirms it. This renders it unlikely that LIP is involved in the planning of movement.