An individual’s emotional state, or mood, has been shown to affect a range of cognitive processes, such as perception, attention, memory and decision-making. The pervasive effects of mood also manifest themselves in language processing, both in semantics and morphosyntax. Behavioural and electroencephalographic data show that people find it easier to integrate mood-congruent information during both word recognition and discourse comprehension. Positive as opposed to negative mood facilitates access to information from semantic memory, and improves the reliability of semantic judgements. Positive mood also improves the processing of morphosyntactic information when resolving pronoun reference and performing subject-verb agreement. In sum, positive compared to negative mood tends to generate greater effects during sentence processing and has been related with improved task performance in psycho- and neurolinguistic studies. However, the mechanisms underlying the effects of mood are not fully understood. I will speak about existing explanations for mood effects and outline the first planned experiment in the doctoral project. In the EEG-experiment, we are going to look at mood effects on the processing of syntactic violations in English, which has not been done before. Participants will read correct sentences and ones with subject-verb agreement errors in a control and two mood-induced conditions. A difference in neural responses to mismatches, if found, might indicate confirmed or disconfirmed expectations about grammaticality and may be a manifestation of mood effects on such cognitive processes as attention and working memory.