As part of the Primary Language Curriculum, there is a particular focus on integrated language teaching and learning and the transfer of skills (ToS) across languages (Irish, English and a variety of home languages). Skills learned in one language can be transferred to another language, and teachers can teach for ToS by exploring similarities and differences across languages in their classrooms. This study employed a single-site case study design using a collaborative inquiry approach to professional learning. Four primary school teachers teaching junior classes in an English-medium school participated in six one-hour professional learning community sessions over eight weeks. Teachers observed lessons modelled by the researcher and subsequently implemented learning activities in their classrooms using the resources provided. Teachers participated in semi-structured individual interviews prior to and following the eight weeks of professional learning. Qualitative research methods were employed to analyse data. Drawing on De Luca’s (2015) framework of collaborative inquiry, template analysis generated key research findings. Findings were supported by the researcher’s reflective journal based on classroom observations and reflections on the professional learning community sessions. Findings show that teachers developed a deeper understanding of the ToS through the collaborative inquiry approach. Teacher PL was supported by, i) observing and implementing shared reading and writing activities, ii) using resources to teach Irish phonics, and iii) explicit planning for ToS. A focused, structured, sustained approach to professional learning where community and coaching were valued, supported teachers to teach for ToS across Irish and English. Increased teacher language awareness of similarities and differences across languages supported teachers’ confidence and competence to teach for ToS. Coaching, modelling of lessons and tailor-made resources may also be beneficial. Engagement in professional learning communities with coaching using a collaborative inquiry approach could support teacher pedagogical content knowledge of ToS across languages in other school contexts.