Teacher professional development is a constantly evolving phenomenon. It is important for effective classroom practice, teacher identity and student learning. This research explores evidence-based teaching portfolios as authentic and continuous professional development involving cross-sectoral and cross-contextual teacher collaboration. Qualitative data analysed from teachers with experience teaching at post-primary, in a national teacher support service, in higher education and in teacher education are discussed. The original claim this paper makes is that many process and practice outcomes elicited during the process of portfolio development are useful for teachers working together across sectors, and therefore valuable for teachers and learners, along and across the education continuum. Key findings indicate that a cross-sectoral group can create knowledge, which is personalised and contextualised to each teacher's teaching philosophy, yet informed by practitioners from different sectors. The merging of a research design through dual structuring of collaborative workshops with individualised mentoring and self-study inquiry enabled meaningful dialogue and reflection among the teachers' from varied settings. Finally, the creation of a personalised and contextualised written teaching portfolio, afforded the teachers evidence of their own professional learning during and following the research process. This collective and individualised learning informed realisations and plans for relational and pedagogical change among the cross-sectoral group.