A challenge faced within the Constructionist learning research community is how to promote learner engagement in critical reflection on their learning experiences. Critical reflection is an important characteristic of deep learning. Cooperative Constructionism, the proposed theoretical framework, utilizes the Constructionism and Communities of Practice learning paradigms as building blocks for incorporating critical reflection into the learning experiences of both learners and teachers. Cooperative Constructionism established a design approach to reflection by using a software tool and teaching methods that facilitate integration of reflective practice into a Constructionist-learning environment. Learners use the Pearls of Wisdom software tool to design and share their reflections on their project design processes. The Reflective Mentor Model is a critical component of the Cooperative Constructionism framework and represents a Constructionist approach to teacher learning and development. Reflective Mentors develop their craft through a continued cycle of constructing and reconstructing their mentoring pedagogy, at both the individual and team levels. The goal is for a Reflective Mentor Community of Practice to develop around supporting Constructionist Cooperative activities. An empirical study was conducted to identify connections between grounded learning theory, existing mentor practices and the proposed Cooperative Constructionism framework. The study took place at the Flagship Computer Clubhouse, an after-school technology centre for 10 to 18 year-olds where learners design projects of their own interest as part of their learning process. Learner activities are supported by adult mentors. Results of the study indicated that a Reflective Mentor Community of Practice resulted in the widespread learner involvement in reflective learning activities. In addition, the Reflective Mentor group had negotiated responsive mentoring practices and a more expansive mentor role in supporting learners and each other within a Constructionist Cooperative.