Knowledge Building principles such as real ideas, authentic problems; epistemic agency; and collective responsibility for advancement of community knowledge convey ways in which Knowledge Building mirrors work in knowledge-creating communities. Previous studies suggest Metadiscourse--discourse about discourse--helps sustain and improve community knowledge. Do students' emotions differ during metadiscourse compared to other discourse contexts? Is metadiscourse even possible in early elementary grades? If so, what emotions are associated with discourse moves requiring high-level reflection on prior discourse? Is it possible that such reflection engenders positive emotions required for sustained creative work with ideas? To address these issues, the authors engaged 22 grade 2 students (7 years old) in monthly metadiscourse sessions over four months, during which they discussed how their ideas changed, what they still wondered about, and what ideas they wanted to pursue. Video recordings of face-to-face sessions, online Knowledge Forum notes, students' interviews, teacher's reflections, and field notes were analyzed using discourse analysis, multi-faceted coding, and correlation analysis. The authors examined how students' emotions and discourse moves differ in Knowledge Building discourse and metadiscourse and correlations between emotions and different discourse moves. The results show: (1) greater levels of enjoyment, reflection on previous ideas, and proposals for new directions for inquiry during metadiscourse sessions; (2) confidence positively associated with explanations and proposals for new directions for inquiry; (3) positive emotions associated with increasingly challenging cognitive work. The relationships between early elementary-grade students' emotions and cognition during Knowledge Building is an underdeveloped area of investigation; in an effort to guide future research a model for regulating emotions in Knowledge Building is presented.