Parental involvement is seen as one of the most malleable factors of the student's home situation, which makes it a relevant subject for schools, educational policies, and research. Though many studies have researched its role in student achievement, effects are not univocal. It is difficult to tell whether these inconsistent results are caused by differences between educational systems and cultural differences, or by the great variation in the methods used to assess student achievement and parental involvement across studies. Large-scale international assessment studies like the Progress in International Reading and Literacy Study (PIRLS) undertaken by the International Association for the Evaluation of Educational Achievement (IEA) therefore provide valuable data. However, a limiting factor may be the extent to which data from different countries can be compared, as cultural differences could influence the international validity of the indicators. The purpose of this research was to develop a suitable psychometric framework for the assessment of the relation between parental involvement and reading literacy, using the PIRLS-2011 data for 41 countries as a case study. The framework included country-specific differences, both at the item and scale level, to gain insight into cultural differences in the parental involvement construct and its relation to student achievement in reading literacy. The project may thus also contribute to the issue of measurement invariance across cultures in large-scale assessment studies. Three main research questions guided the project: (1) Which dimensions of parental involvement can be discerned and to what extent is there empirical evidence that these dimensions are related to student attainment?; (2) To what extent are there any cultural differences (differences between countries) in the constructs that measure dimensions of parental involvement?; and (3) To what extent are the different dimensions of parental involvement related to student achievement in reading literacy, taking into account student background characteristics and differences between countries? Technical Details on the Implementation of the Bi-factor Model is appended. (Individual chapters contain references.)