Reducing inequity is the moral imperative confronting today's educational leaders. Central to reducing inequity is leaders' ability to solve the school-based problems that contribute to it, while building the positive and trusting professional relationships required for teachers to commit to the hard work of improvement. A theory of collaborative problem-solving informed our intervention designed to improve the effectiveness of leaders' behaviour as they worked with their teachers to accelerate the reading achievement of students yet to reach age-related standards. A concurrent mixed methods design was used to evaluate the impact of the intervention by analysing transcripts of interviews and leader-teacher conversations and student reading achievement data. Leaders' effectiveness in their conversations improved significantly as did the reading outcomes of their target students. Our findings suggest that even short interventions grounded in strong theory with appropriate learning opportunities can affect a positive change in leadership behaviour and student outcomes.