Event-related potentials were recorded in 2 experiments while participants read sentences in a word-by-word congruency judgment task. Sentence final words were either congruent, semantically anomalous (Experiments 1 and 2), or neutral (Experiment 2) with respect to sentence context. Half of all final words referred to concrete and half to abstract concepts. A different scalp distribution of the N400 to concrete and abstract final words was found for anomalous and neutral, but not congruent sentences. Although the interaction of context and concreteness is consistent with the context-availability model, the differential scalp distribution of effects for concrete and abstract words, as well as larger context effects for concrete words, was interpreted as being more consistent with an extended dual-code account of semantic processing.