Mentoring is one important construct to support novice principals in this time of change. This study investigates the impact of a district-developed handbook to support co-constructed mentoring practices and cultivate a learning culture within a suburban school district. The handbook offered a framework of interactive systems and tools for communication and relationship building including guiding questions for deep discussion and analysis of practices and culture, data collection, and webinars. Use of the handbook was perceived to deepen instructional leadership capacity and to foster the colearning of the leaders through shared experiences. An emerging emphasis on professional learning among the participants in the mentoring program was unanticipated. Implications of these findings are offered within a specific district context for cultural shifts and improved student outcomes.