Abstract The present study aims to explore the effect of elicitation-task design on speech rate. The data derives from the Czech learner subcorpus of the Louvain International Database of Spoken English Interlanguage (LINDSEI_CZ), its native English counterpart the Louvain Corpus of Native English Conversation (LOCNEC) and a corpus of native Czech recorded by the same speakers as in LINDSEI_CZ. Speech rates in words per minute are compared using ANOVA. Significantly lower speech rates are found especially in the picture-based task, showing that such tasks are cognitively demanding both for learners and natives. Differences between monologic and dialogic tasks are smaller and not statistically significant. The study explores possible reasons for these differences and draws implications for corpus design and research design as well as for language assessment.