Empirical research repeatedly shows cross-country differences in the extent and distribution of socioeconomic inequalities in educational achievement. This observation is the starting point for the comparative DICE-project (Development of Inequalities in Child Educational Achievement: A Six-Country Study). It aims to improve the understanding of child development by socioeconomic status, operationalised in terms of parental education in six countries: France, Germany, Japan, the Netherlands, the United Kingdom, and the United States. The project moves beyond cross-sectional and single country snapshots and examines the development of inequalities from 3 years of age up to the end of lower secondary schooling. In this contribution, we introduce the six countries. First, by synthesizing data from a range of international databases we provide a rich and multidimensional characterisation of macrostructural conditions in each country. Linking the contextual situation in the DICE-countries to general theoretical assumptions about the effects of macrostructural conditions, we highlight the implications for cross-national differences in inequalities in educational achievement. Second, we analyse PISA data providing information about achievement test scores at age 15. We study how the different packages of macrostructural characteristics described in the contextual section are reflected in terms of educational inequalities by the end of lower secondary schooling in each country.