The present paper reports results from three ERP studies showing components which reflect the processing of different word stress violations dependent on distinctive task properties (conscious vs. unconscious processing). The main findings were that the presentation of an incorrect stress pattern led to an N400-like component indicating increased costs in lexical retrieval. Such a component is not dependent on the task during the processing of stress violations. Furthermore, an enhanced positivity effect (P300) reflects a stress mismatch detection only if stress judgment was explicitly required in the task.