Socioeconomic characteristics are persistently and systematically related to academic outcomes, despite long-standing efforts to reduce educational inequality. Ireland has a strong policy focus on alleviating educational disadvantage and has seen significant improvements in mathematics and science performance in recent years. This study investigates patterns of socioeconomic inequalities in 4th grade students’ performance in mathematics and science between 2011 and 2019. Two measures of inequality are examined: (i) inequality of achievement, i.e., the degree of variability in student performance and (ii) inequality of opportunity, i.e., the extent to which student performance is related to background characteristics.