Choral performance requires several interpretative and technical choices by the conductor. One of the elements about which the conductor makes choices is the diction of the sung text, since Western musical notation does not specify the precise instant of articulation, the duration or the dynamic of vowels and consonants. Choral conducting handbooks generally discuss diction in terms of uniformity of pronunciation and clearness of enunciation, or also in terms of its relationship with choral blend and/or with a legato line. However, few writings on choral conducting are explicit in relation to possible durations, dynamics and/or instants of articulation of vowels and consonants, and even rarer are those which exemplify how these choices may contribute to an expressive performance. In the last decades, researches on expressivity in music performance have increased, yet few of such researches mention that the way one pronounces a text may play a part in expressivity. Moreover, little is known about the effects of an expressive diction specifically in choral performances. In this research, I investigate conductors’ interpretative choices regarding text diction in choral music sung in German, aiming to identify the effects of these choices on the expressivity of choral performance. My research uses mixed methods and techniques, which include bibliographical studies, case studies, interviews, score analyses, as well as recording analyses made with the software Sonic Visualiser. The first part presents the research’s starting points, which refer to questions on choices in performance and on expressivity in performance. The second part presents the bibliographical studies, which include an analysis of writings about choral conducting and data collected in the interviews I did with six conductors. In this part I discuss German diction for singing, conductor’s suggestions with respect to text diction (especially as regards the duration, the dynamic and the instant of articulation of vowels and consonants), the relationships between text articulation and musical articulation, and the expressive possibilities of diction. The third part presents the case studies, in which I analyse scores and recordings of choral works by J. S. Bach, F. Schubert and J. Brahms, and describe the effects of different choices related to diction. The fourth and last part compares data presented in the bibliographical studies and in the case studies. In this final part, I discuss the relationships between the recordings and the researched literature in terms of the interpretative choices regarding text diction, the influence of text articulation on musical articulation, and the role of diction in the expressivity of choral performance. Results suggest that in particular situations text diction can play a central role in performance expressivity, eventually being as significant as (or perhaps even more than) aspects more commonly analysed in researches, such as variations in tempo, portamento or vibrato. Finally, I suggest two elements concerning text diction that may contribute to an understanding of the experience of listening to an expressive performance: a sense that the musicians are part of the music, as well as a sense of being in the present moment.