The acquisition of new knowledge is a critical task for software development. IT companies spend considerable resources in the training of their employees to succeed in a continuously changing industry. Depending on the voluntary commitment of their contributors, initiatives developing Free Libre Open Source Software (FLOSS) identified members' learning and their retention as vital. Although contributors' knowledge building has been repeatedly found to facilitate their project continuance, FLOSS projects are lacking operational advices on how to assist their members' learning. Drawing on previous literature which emphasizes project members' social interactions and their practical experiences to build new knowledge, we propose mentoring as a training method for FLOSS projects. Based on organizational experiences, we propose a measure to evaluate mentoring as an appropriate strategy for FLOSS initiatives to facilitate individuals'
learning and to retain their contributors on longitudinal base.