Background/Context: Some school districts across the country have begun to convene principals in professional learning communities (PPLC) as a strategy to help principals develop as instructional leaders, and they have designated executive-level central office staff to lead the PPLCs. Extant research suggests the promise of PPLCs for supporting principal development but raises significant questions about what central office leadership of such PPLCs entails and if central office administrators are up to the task. Purpose/Research Questions: This paper examines the following questions: To what extent are the central office administrators who run PPLCs actually doing so in ways consistent with the goal of supporting principals' learning to strengthen their instructional leadership? What conditions help or hinder them in the process? Research Design: We explored these questions with an embedded, comparative, qualitative case study of six PPLCs convened by central office administrators in one urban district. We used a conceptual framework, derived from socio-cultural learning theory, to help us identify and understand central office administrators' practices in the PPLCs. Our data sources primarily included direct observations of 105 hours of PPLC meetings, supplemented with 46 semi-structured interviews and reviews of more than 150 documents. Findings: We found that the central office administrators varied in how they participated in the PPLC meetings, particularly in terms of the extent to which they engaged in the teaching practices identified in our conceptual framework. The central office administrators who most frequently engaged in those practices were also the central office administrators we associated with such positive results as their principals' engagement in progressively more challenging instructional leadership activities during PPLC meetings, and principals' detailed reports of the value of the PPLC meetings to their development as instructional leaders. Key mediators of central office administrators' participation in the meetings include their executive-level positions, other central office staff and principal demands, the availability of professional development, and their own orientations to the work. Conclusions: Our findings suggest that central office administrators are able to buck institutional trends and productively lead PPLCs provided (1) they come to the work with a teaching rather than directive or managerial orientation, and (2) central offices intentionally create other conditions to foster their success. Future research should aim to further understanding of principal learning in PPLCs and how central office and other leaders can productively facilitate the process.