Investigated the hypothesis that the affective valence of an event and the resulting mood state can influence causal thinking independently of the event's expectedness. 45 university students completed an ostensible professional skills test and received either success or failure feedback in relation to a criterion set by the experimenter. The subjective probability of success was varied by informing Ss about the distribution of success and failure in a comparable population (either 23 or 77% were said to meet the criterion). Results indicate a pronounced valence effect: The intensity of causal reasoning and the number of possible reasons reported for the outcome were greater after negative than after positive feedback, independent of the a priori probability of the outcome. No evidence for an increase in causal explanations after unexpected, as compared to expected, events was obtained. (French & German abstracts) (PsycINFO Database Record (c) 2007 APA, all rights reserved)