This study examined the role of reading comprehension skill in the relationship between problem solving ability and growth in maths achievement. Within this analysis framework, group differences based on language background were also examined. The participants for this study are government school students (N=5886) in grades 3–8 in Victoria, Australia.Results showed no evidence of moderation by language background, implying that language background does not have an effect on how RC skill mediates the relationship between PS ability and growth in maths achievement.Partial mediation is confirmed in more focussed tests of mediation using regression analysis. Two datasets using independent measures provide corroborating evidence that RC skill may be partially mediating the relationship between PS ability and growth in maths. In addition, findings show that these mechanisms hold uniformly regardless of language background, and that with no evidence of group differences with respect to the partial mediation model, the results have better generalisability to the student population. These findings have important implications for future system-wide implementation of large scale interventions on Australia's linguistically diverse classrooms.