Rastle et al. (2004) reported that true (e.g., walker) and pseudo (e.g., corner) multi-morphemic words prime their stem words more than form controls do (e.g., brothel priming BROTH) in a masked priming lexical decision task. This data pattern has led a number of models to propose that both of the former word types are "decomposed" into their stem (e.g., walk, corn) and affix (e.g., -er) early in the reading process. The present experiments were designed to examine the models proposed to explain Rastle et al.'s effect, including models not assuming a decomposition process, using a more sensitive priming technique, sandwich priming (Lupker & Davis, 2009). Experiment 1, using the conventional masked priming procedure, replicated Rastle et al.'s results. Experiments 2 and 3, involving sandwich priming procedures, showed a clear dissociation between priming effects for true versus pseudo multi-morphemic words, results that are not easily explained by any of the current models. Nonetheless, the overall data pattern does appear to be most consistent with there being a decomposition process when reading real and pseudo multi-morphemic words, a process that involves activating (and inhibiting) lexical-level representations including a representation for the affix (e.g., -er), with the ultimate lexical decision being based on the process of resolving the pattern created by the activated representational units.