Based on the analysis of conversations between French and Australian English speakers discussing various topics, including their experiences as non-native speakers in France or Australia, this book combines subjective personal testimonies with an objective linguistic analysis of the expression of opinion in discourse. It offers a new perspective on French and Australian English interactional style by examining the discourse markers I think, je pense, je crois and je trouve. It is shown that the prosody, intonation unit position, and the surrounding context of these markers are all fundamental to their function and meaning in interaction. In addition, this book offers the first detailed comparative semantic study of the three comparative French expressions in interaction.