How quickly do different kinds of conceptual knowledge become available following visual word perception? Resolving this question will inform neural and computational theories of visual word recognition and seman- tic memory use. We measured real-time brain activity using event-related brain potentials (ERPs) during a go/nogo task to determine the upper limit by which category-related knowledge (living/nonliving) and action-related knowledge (graspable/ungraspable) must have been accessed to influence a downstream deci- sion process. We find that decision processes can be influenced by the living/nonliving distinction by 160 ms after stimulus onset whereas information about (one-hand) graspability is not available before 300 ms. We also provide evidence that rapid access to category-related knowledge occurs for all items, not just a subset of living, nonliving, graspable, or ungraspable ones, and for all participants regardless of their response speed. The latency ofthe N200 nogo effect by contrast is sensitive to decision speed. We propose a tentative hypothesis of the neural mechanisms underlying semantic access and a subsequent decision process.