Online learning, case discussions, and stochastics instruction have all become increasingly active strands of research in mathematics education. This study integrates the three strands. The nature of the discourse during an online case discussion among prospective secondary teachers is analysed. The case focused on the teaching and learning of a version of a classic statistical sampling problem. Participants formed several threads of conversation in discussing the case. During the online discussion, the prospective teachers conversed about multiple elements embedded in the case, including: mathematical issues, assessment of students, pedagogical strategies, the context of the case, and writing choices made by the case author. The discussion also contained substantive contributions from individuals who were normally silent in face-to-face class sessions, and allowed extended time for participants to craft responses to one another. (Contains 3 tables and 3 figures.)