This article examines how principals describe the nature of relationships and presence (or absence) of relational trust among teachers, and between the teachers and the principal in the discourse of professional learning communities. Participants were 12 school principals from urban, suburban, and rural communities in Manitoba. In the discourse of learning communities, the notion of trust is articulated as being relational in its orientation and developed around group norms of safety, risk-taking, and change orientation. The existence of relational trust appears to have the effect of fostering collaboration and promoting willingness among staff to grow professionally. The study also suggests the important role that principals play in establishing relational trust as a precondition for the growth of a professional learning community. Because relational trust appears to be critical to the functioning of a professional learning community, it may be unlikely that substantive school improvement can be achieved without close attention to it.