Ireland's government placed a renewed focus on the teaching and learning of numeracy with the publication of a national strategy in 2011. Whole-school planning for numeracy was already a requirement for disadvantaged schools also known as Delivering Equality of Opportunity in Schools (DEIS) in Ireland. This single site case study explored how a disadvantaged school was teaching numeracy across the curriculum. It was discovered that teachers were unclear about the difference between numeracy and mathematics. Teachers' life experiences of mathematics shaped their views towards numeracy. Leadership played a role in shaping teachers' views of the importance of numeracy. Whilst all teachers could see the relevance of teaching numeracy in their subject area, the majority were unaware of what the school improvement plan for numeracy contained. The findings suggest the need for teachers to understand the concept of numeracy, the need for professional development to address this, in addition to developing teachers' identities and pedagogical practices in this area. Schools need to consider how leadership can put support in place to enable teacher learning. Policymakers need to consider and distinguish between mathematics and numeracy, and support schools' engagement with cross-disciplinary, interdisciplinary and transdisciplinary approaches to embedding numeracy across the curriculum.