Which cognitive processes are reflected by the N400 in ERPs is still controversial. Various recent articles (Lau et al., 2008;Brouwer et al., 2012) have revived the idea that only processes during word-retrieval (such as automatic spreading activation, ASA) are strongly supported, while post-lexical integrative processes are not. The present ERP study replicates a behavioral study by McKoon and Ratcliff (1995) who demonstrated that a prime-target pair such as finger -hand shows stronger priming when a majority of other pairs in the list share the analogous semantic relationship (here: part-whole), even at short stimulus onset asynchronies (250 ms). We created lists with four different types of semantic relationship (synonyms, part-whole, category-member, opposites) and compared priming for pairs in a consistent list with those in an inconsistent list as well as unrelated items. Highly significant N400 reductions were found for both relatedness priming (unrelated vs. inconsistent) and relational priming (inconsistent vs. consistent). These data are taken as strong evidence that N400 priming effects are not exclusively carried by ASAlike mechanisms during lexical retrieval but also include post-lexical integration in working memory. The present findings will be linked to a neurocomputational model for relational reasoning (Knowlton et al., 2012) and to recent discussions of context-dependent conceptual activations (Yee & Thompson-Schill, 2016).