English Language Learners (ELLs) are at-risk of academic failure due to a lack of English Academic Language (AL) proficiency (August & Shanahan, 2006). Irish primary schools are increasingly diverse linguistic landscapes (Central Statistics Office, 2016; 2011) and teachers are frustrated by a lack of appropriate Professional Development (PD) for their work with ELLs (Gardiner-Hyland & Burke, 2018). Thus emerges a rationale for Irish research to provide PD for teachers to support ELLs’ AL development. The researcher proposes that an English-Irish oral narrative programme, Tell-aTale | Inis Scéal (TaTIS), can offer teacher PD for linguistically diverse contexts and support the AL development of children (aged 5–6) through oral narrative retell. A Theory of Change framework (Weiss, 1995) supports this proposal by presenting a clear rationale for TaTIS planning, implementation, and evaluation (Reinholz & Andrews, 2020). Sociocultural Theory (Vygotsky, 1978), Interactionist Theory (Bruner, 1981), Common Underlying Proficiency Theory (Cummins, 2000) and the Gradual Release of Responsibility Model (Pearson & Gallagher, 1983) underpin TaTIS, while a Sociocultural Mentoring Model (Kram, 1983; Vygotsky, 1978) supports PD for its effective delivery by participant mainstream and support teachers. The researcher explored TaTIS design, development, and delivery through a fivephased Multiple Embedded Case Study. Firstly, the researcher conducted a literature review to inform the design principles of TaTIS and PD. Secondly, the researcher bridged such theory with practice by piloting PD and TaTIS delivery with stakeholders in three linguistically diverse classrooms. Data collection methods were also trialled during this phase and finalised for the main study to include focus group discussions, PD discussions, semi-structured interviews, observations, and draw-and-tell interviews. Thirdly, the researcher collected data in six similar settings to discern participant teachers’ PD experiences, bilingual narrative pedagogy experiences, and participant children’s responses to TaTIS. Fourthly, the researcher used Thematic Analysis (Braun & Clarke, 2006) to generate a thematic framework of data findings. Finally, the researcher collated a report of such findings to offer recommendations for future educational policy, practice, and research. The researcher found no evidence of a previous English-Irish oral narrative programme, nor of any international bilingual oral narrative programme that used ELLs’ second and third languages. Thus, this study offers these unique contributions regarding stakeholder experiences of participation. Additionally, the researcher employed a qualitative research design in an otherwise quantitatively dominated field, offering a different methodological lens for oral narrative programme exploration.