This study documents the enduring impacts of a workplace music mentoring programme for generalist classroom teachers in early childhood school settings in Australia. The study draws on follow-up interviews with mentors, teachers and principals from five of 11 participating schools one year after the programme. This study identifies participant perceptions of "enduring" outcomes, "enduring" effective mentoring, and effective mentor qualities. Two researchers undertook thematic analysis independently and conducted iterative discussions to refine the emerging themes. Enduring outcomes for mentors, teachers and students included: (1) music mentoring as collaborative self-development; (2) identification and realisation of individual and collective goals for music teaching; (3) reflection, feedback and joint planning informing learning; (4) integration of music into daily activities, lesson transitions, school culture; (5) creating a community of music practice in and across schools; and (6) improved classroom climate and enhanced student engagement and positive behaviours. Enduring qualities of effective music teaching included: (7) building teacher confidence and competence for music leadership; (8) observation of expert practice as a learning tool; (9) focused feedback informing lesson planning and implementation; and (10) specialised, collaborative workplace mentoring. Enduring qualities of effective music mentors included sensitivity, responsiveness, situational awareness, flexibility, and subject and pedagogic expertise.