In an era of increased transnationalism, cultural and linguistic diversity has become a prominent feature of Irish society. Between the years of 1995 and 2008, Ireland experienced high rates of inward migration for the first time, which has subsequently led to an emerging second generation of migrants in Ireland (Röder, Ward, Frese, & Sánchez, 2014). While the Polish community is the largest non-Irish group in Ireland, little is known yet about the unique linguistic and cultural challenges faced by Polish migrant and transnational families in Ireland. Family language policy (FLP) research depicts "how languages are managed, learned and negotiated within families" (King, Fogle, & Logan-Terry, 2008, p. 907). FLP studies of migrant and transnational families in Ireland are limited and the current study aims to explore how individual members within Polish families in Ireland jointly construct and negotiate FLP in the home domain. The current study contributes to the field of FLP by being inclusive of the voices of children as active agents in their language use and learning. An ethnographic approach employing qualitative methods within a constructivist paradigm was deemed the most appropriate way to investigate FLP formation and negotiation in the home domain. The theoretical framework adopted for the research sought to analyse how language socialisation processes and ethnolinguistic identity construction interact with the language ideologies, practices and management strategies of parents and children. The influence of multiple forces on FLP formation, both inside the home and at wider societal level (Curdt-Christiansen, 2014, 2018; Spolsky, 2004) were also considered in the research. The study comprised two phases of research. During the first phase, a qualitative focus group interview and six individual interviews were conducted with Polish migrant and transnational parents (n=12). These findings informed the development of the second phase of the research, constituting ethnographic case studies of five families. Participant sampling reflected different family structures including two-parent families, a single-parent family and transnational families living between Poland and Ireland. Data collection methods included interviews, observations in the home, audio and video recordings and reflective language diaries. Thematic analysis (Braun & Clarke, 2006, 2012) was employed to analyse the data. The findings revealed the inextricable link between language and identity formation among family members. The findings also demonstrated how FLP is continuously being negotiated and reconstructed to suit the everchanging needs and circumstances of migrant and transnational families.