The purpose of this study is to compare how Swedish school principals understand basic values that are important in fulfilling the Swedish national curriculum, Curriculum 1994 (a new curriculum, Curriculum 2011, which came into operation in autumn 2011, has only minor differences compared to the common text in Curriculum 1994), considering Bronfenbrenner's ecological systems theory. Two rounds (in 1998 and 2009) of somewhat different interview questions were conducted in the southern part of Sweden, and the data analysis technique of content analysis was chosen. The main results show a need to add levels into the original Bronfenbrenner ecological systems theory regarding basic values in the Swedish compulsory school system.