Teacher enthusiasm is linked to various positive outcomes. However, most teacher enthusiasm research is based on correlational data. Therefore, no causal inferences can be drawn. To overcome this limitation, a between-subject experimental design (N = 163) was used to analyse the effects of teacher enthusiasm on instructional quality. Two versions of an educational podcast were developed: A neutral and an enthusiastic version. While the wording was kept identical between both versions, the speaker was instructed to read the podcast script either in a neutral or in an enthusiastic manner. The results show that listening to the enthusiastic version resulted in more positive instructional quality ratings: Participants who listened to the enthusiastic version rated it as more interesting and exciting; they enjoyed the listening process more; had a higher motivation to learn more about the topic; evaluated the podcast host as more trustworthy; and gave the podcast a higher overall rating.