Déantar cur síos san alt seo ar thaithí cúigear múinteoirí agus príomhoide amháin ar an bhFoghlaim Chomhtháite Ábhar agus Teangacha (FCÁT) a chur i bhfeidhm tríd an tríú teanga i mbunscoileanna lán-Ghaeilge. Tá cáil ar FCÁT mar chur chuige atá éifeachtach leis an dara teanga a theagasc. Is éard atá i gceist le FCÁT, ná go múintear ábhar nó cuid d’ábhar trí mheán an dara teanga nó teanga bhreise. Ba scéim phíolótach cheannródaíoch a bhí sa taighde seo mar go raibh FCÁT á chur i bhfeidhm le foghlaimeoirí óga, ag baint leasa as an tríú teanga i suíomh an tumoideachais lán-Ghaeilge. Chomhtháthaigh na múinteoirí a bhí páirteach sa taighde, teanga Eorpach (An Fhraincis/An Ghearmáinis), leis an bhfoghlaim ábhair in ábhar scoile amháin le linn na scoilbhliana. Bhí réimse rang-ghrúpaí agus ábhar i gceist agus cuireadh múnlaí éagsúla de FCÁT i bhfeidhm ag brath ar inniúlacht na múinteoirí sa sprioctheanga. Bailíodh eolas cáilíochtúil faoi eispéiris na múinteoirí ó cheistneoir agus grúpa fócais. Cé gur taighde ar scála beag atá sa taighde seo, is ábhar taighde nuálach é a thugann léargas ar chuid de na saincheisteanna a bheadh le plé dá mbeadh FCÁT le cur i bhfeidhm i scoileanna lán-Ghaeilge ar bhonn níos leithne amach anseo. Eascraíonn ceisteanna maidir leis na hábhair seo a leanas: inniúlacht múinteoirí sa sprioctheanga, forbairt ghairmiúil leanúnach do mhúinteoirí, torthaí foghlama teanga FCÁT agus soláthar áiseanna do FCÁT. Is í an phríomhcheist a eascraíonn ón taighde ná, cén múnla FCÁT ab fheiliúnaí do shainchomhthéacs na mbunscoileanna lán-Ghaeilge in Éirinn. Abstract This article reports the experiences five Irish-medium primary teachers, and one Irish-medium principal of implementing Content and Integrated Learning (CLIL) through a third language in Irish-medium primary schools. CLIL is recognised as an effective approach to second language teaching. It entails the teaching of a subject, or a part of a subject through the medium of a second or an additional language. In this pioneering pilot study CLIL was implemented with young learners through a third language in an Irish-medium immersion setting. The teachers involved in the project integrated a European language (French/German), with content learning in one subject throughout the school year. There were a variety of class groups and subjects involved, and teachers adopted various approaches to CLIL in accordance with their own linguistic proficiency. Data relaying the teachers’ experiences and approaches to CLIL were gathered from a questionnaire and focus group interview. This small scale innovative research provides an insight into prominent questions for discussion if CLIL is to be implemented in Irishmedium schools on a wider basis. Questions arise concerning: language teacher proficiency, continuous professional development for teachers, language learning outcomes for CLIL, and the provision of specifically designed CLIL resources. A key question arising from the study is what model of CLIL would be most suitable for the specific context of Irish-medium primary schools in Ireland.