In 3 experiments, we tested how domain-related knowledge (in the clinical psychology domain) influences clinical diagnosis inference generation during text comprehension. Clinical diagnoses are considered here as explanatory trait inferences. To analyze the time course of clinical diagnosis inferences, experts and novices were compared. In Experiment 1, 21 texts were presented in a lexical decision task using a stimulus onset asynchrony of 500 ms. Reaction times were faster for experts than novices. In Experiment 2, 8 texts were presented using a reading time task with sentence-by-sentence presentation. Only in the case of the experts did we detect significant differences in reading times between the critical and the neutral sentences. In Experiment 3, clinical and narrative texts were presented to analyze whether these differences between experts and novices were caused either by previous knowledge or by general reading skills. The results showed advantages for experts, but only in the case of clinical texts. These results suggest that clinical diagnosis inferences are made by the experts online and that previous knowledge is a decisive factor in this process.