Slot-filling theories of conceptual combination assume that both constituent concepts are activated before they are combined. However, these theories have difficulty in explaining why combined phrase features are sometimes more available than the features of the constituent nouns. In this study, we investigate the time course of conceptual knowledge activation. Using three verification tasks of varying complexity we demonstrate that basic taxonomic knowledge is retrieved more quickly than modal specific conceptual features. Applying this finding to conceptual combination, we demonstrate that participants take longer to reject combinations requiring the activation of instance specific features (e.g. frog tail) than those that can be rejected based on more generalized taxonomic knowledge (e.g. daffodil tail). These findings provide convergent evidence that conceptual knowledge is activated dynamically and selectively rather than all at once. We discuss the implications for existing theories.