Earlier research has indicated that some characteristics of facial expressions may be automatically processed. This study investigated automaticity as evidenced by involuntary interference in a word evaluation task. Compound stimuli, consisting of words superimposed on pictures of affective faces, were presented to subjects who were given the task of evaluating the affective valence of the words while disregarding the faces. Results of three experiments showed that word evaluation was influenced by the concurrently shown affective faces. Overall, negative words were found to require longer latencies, indicating that more processing resources are invested in negative than in positive stimuli. This speed advantage for positive words was modified by the faces. Negative words were facilitated, relative to positive ones, when shown with a negative expression, e.g. a sad face. Correspondingly, negative words were inhibited, relative to positive ones, when shown with a positive expression, e.g. a happy face. The results are consistent with automatic, involuntary semantic processing of affective facial expressions.