The aim of this chapter is to explore the association between student achievement in mathematics and six selected variables of parental involvement. We estimate a linear regression model using TIMSS 2015 data from 18 European countries. Our model allows us to explore the associations between 4th grade students’ achievement in mathematics and the variables of parental involvement, while controlling for further characteristics of the students’ wider school and home contexts, as identified in the TIMSS 2015 context questionnaire framework. We show an internationally observable association between two out of the six parental involvement variables available in the TIMSS 2015 framework: ‘home resources for learning’ and ‘help with homework’. Students with access to more resources for learning tend to have a higher achievement in mathematics. A positive association was also observed for ‘school attendance’ and ‘early literacy and numeracy activities’, although this was statistically significant in most, but not all countries. In the case of the remaining ‘parental attitudes towards mathematics’ and ‘parental perceptions of school performance’, the association was ambiguous, with statistically significant associations observable only for a few countries and insignificant associations varying in their direction, most likely moderated by factors beyond parental involvement.