In recent decades, large-scale assessments in Ireland have revealed consistent trends, phases of change, and some surprises. This brief explores how data from large-scale assessments informed Ireland's "National Literacy and Numeracy Strategy 2011-2020," particularly regarding priorities, target-setting, and monitoring. It also examines how related initiatives including curriculum redevelopment and standardized testing reform have reflected large-scale assessment findings. Looking ahead, the authors outline how large-scale assessments can inform Ireland's next "National Strategy" to 2033, which encompasses digital literacy along with literacy and numeracy. More broadly, using Ireland as a case study, important issues are identified for policymakers in other countries to consider when using ILSA (international large-scale assessment) data within their own national contexts.