There is evidence that books in the childhood home impacts educational and occupational attainments. This ‘book effect’ exists independent of parental socioeconomic status. It exists in countries all over the world for which data are available. However, the mechanisms underlying the book effect are largely speculative, calling for further testing. Here we discuss three theoretical explanations for the book effect: human capital, cultural capital and scholarly culture. Then using CILS4EU data in four countries and structural equation modeling, we test hypotheses derived from these divergent theories. We find the direct effect of books does not differ between native and immigrant adolescents in predicting 9th grade language aptitude. Moreover, this effect does not vary much by country or by the degree of immigration background (one or both parents), it appears universal in these data. Reading-habits and primary language spoken at home explain only part of the book effect suggesting that the presence of books measures something symbolic. This leads us to a discussion of books and documents containing printed words, and how awareness of books may develop in children.
