Studies on music reading have provided insights into the cognitive processes in sight singing. However, there has been limited research on sight singing in a group setting. This study aims to assess how choral singers approach music reading as they perform previously unfamiliar choral scores together. We addressed (1) how singers’ gaze direction is distributed over staff systems, and (2) how their gaze behaviour is influenced by note density and repeated practice. Four quartets, a total of sixteen experienced singers, performed eight Baroque music excerpts three times, while the singers’ eye movements were recorded. Eye-movement measures were analysed in conjunction with the singers’ views regarding their music reading, obtained through questionnaires and group discussions. Results reveal that besides reading their own voice lines, singers typically inspected the neighbouring lines, seeking visual cues to coordinate the performance. The results of a generalised linear mixed model analysis underscore the substantial influence of note density on fixation durations on one’s own lines, but not on other voices’ lines. Practice, on the other hand, exhibited effects only on average fixation duration for one’s own lines, with no significant impact observed on other lines. The study provides evidence of coordination between an actual sight-reading process and a parallel information-gathering process that helps singers relate their parts to the overall musical structure.