This paper examines how middle leaders in Irish primary schools lead and facilitate professional learning (PL) within the cultural, material, and social conditions of their schools. Drawing on a multisite case study and framed by the theory of practice architectures and scholarship on transformative PL, this paper highlights how middle leaders’ capacity to shape collaboration is contingent, negotiated, and often fragile. Across the cases, discursive norms drawn from national policies provided authority but also narrowed PL into cycles of compliance. Material conditions, especially time, were precarious, leaving MLs reliant on goodwill or episodic opportunities to convene colleagues. Social–political relations of trust determined whether MLs were positioned as task managers reporting upwards or as facilitators of collective dialogic meaningful PL. The findings suggest that while middle leaders are well placed to foster inquiry and create communicative spaces, the dialogic depth needed for transformative PL was rarely sustained. We argue that middle leaders’ influence lies less in formal designation and more in their ability to broker dialogue under shifting conditions. Strengthening middle leadership requires legitimising inquiry, structurally protecting time, and recognising relational authority as central to leading professional learning.