This qualitative study examined the role that middle leaders and their professional learning communities (PLCs) play in focusing teachers’ attention on student learning. The study presents an analysis of this phenomenon across multiple school types in Hong Kong and Shenzhen, China using case study methodology as a vehicle to uncover factors which support and inhibit the work of middle leader-led PLCs in varying school contexts.This thesis demonstrates that middle leaders use a plethora of skills and exhibit myriad attributes to form and maintain their teacher teams. The nine critical attributes presented here: (a) shared values and vision; (b) collective responsibility; (c) reflective professional inquiry; (d) collaboration, (e) promotion of group, as well as individual, learning; (f) mutual trust, respect and support among members; (g) inclusive membership; (h) looking beyond the school for sources of learning and ideas and (i) shared leadership, when present, create an environment where robust structures can be formed. Such structures create a forum for teachers to collaborate on instructional initiatives, curriculum enactment, teacher empowerment and team building. These opportunities for professional dialogue were welcomed by middle leaders and teachers across the study.The findings from the interviews with middle and senior leaders, as well as with members of their PLCs, revealed there were five aspects that impacted middle leaders effectiveness with their prospective teams, depending on their school context: (a) funds for professional development; (b) the competitive environment; (c) staff stability and longevity; (d) the leadership style of the principal and (e) middle leader authority and role recognition. The nexus between school type and these five aspects impact on the middle leaders’ actions when working with their teacher teams. Middle leaders adapt their leadership to their situational contexts and customize strategies which cohere to the school’s ethos