Students who can regulate their own learning are proposed to gain the most out of education, yet research into the impact of self-regulated learning skills on performance shows mixed results. This study supports the link between self-regulated learning and performance, while providing evidence of grade- or age-related differences. Australian students from Grades 5 to 8 completed mathematics or reading comprehension assessments and self-regulated learning questionnaires, with each response ranked on a hierarchy of quality. All assessments were psychometrically analysed and validated. In each cohort and overall, higher performing students reported higher levels of self-regulated learning. Still, age-related differences outweighed performance differences, resulting in significantly lower reported usage of self-regulated learning skills in Grade 7 students compared to those in Grades 5, 6 and 8. These findings suggest that either age or school organisational differences mediate students' self-regulated learning, counteracting ability-related associations.