A study compared the effects of cognitive complexity on the speech production of 14 advanced non-native speakers of English and 14 native English-speakers. Cognitively simple and complex tasks were distinguished based on text type (narrative versus expository). Subjects read one narrative and one expository text in separate sessions, then wrote about the texts (short-term recall), had an unrelated conversation, and were asked to reproduce the texts orally. Three types of measure were used: fluency measures (pause length, phonation time, speech rate, articulation, phrase length), proposition recall measures (recall of simple propositions in the text in question), and reading time. Results indicate that the native English speakers (L1s) recalled an equal percentage of propositions on both text types, and the non-native speakers (L2s) recalled a higher proportion of propositions in the narrative text, suggesting that cognitive complexity has a more robust effect on L2s than L1s. In addition, it was found that fluency (speech rate and phrase length) varied significantly for both L1s and L2s across text types, while articulation rate varied for L2s only. A subtle effect appeared in the interaction between phonation time and the number of propositions reproduced in both groups. Subjects' private speech emerged as a significant factor. (MSE)