An experiment is presented which tested the hypothesis that people would provide different causal explanations for an occurrence depending on the ‘causal background’ against which the occurrence is considered. Results indicated that in devising an explanation for an occurrence, people might compare the target episode to contrasting background instances in which the episode did not occur. Data supported the hypothesis that distinctive features between the target episode and the contrasting background instances form the basis of people's causal explanations. The experiment also examined the hypothesis that background effects might be more difficult to produce when subjects are asked to select possible causal explanations from a list vs. providing explanations of their own. However, results indicated no significant effect for response mode on the production of background effects in causal explanati