The purpose of this article is to analyse the relations between students’ cultural and social capital and their competence test results in the field of the Polish language. The data come from the research carried out in 2013 in 60 middle schools in 5 provinces of Poland. Students filled in survey questionnaires regarding their school and family environment and 3 competence tests. Two types of socio-cultural capital were distinguished – soft and hard capital. The hard socio-cultural capital affects approximately 10% of the students’ results. If the soft and hard capital resources and the extent of identification with school were increased by one level, this would result in an average increase in the 1st form students’ results of the test regarding cultural texts analysis and interpretation by 21.4%.