This study tested whether socio-economic status (SES) moderated the association between the psychosocial constructs included in the attitude-social influence-self-efficacy (ASE) model and fruit intake in Norwegian schoolchildren. The sample consisted of 962 Norwegian sixth graders, mean age 11.3 years. They were split into three SES groups, and multi-group structural equation modeling (MSEM) was used. Children in the highest SES group reported eating fruit more frequently and reported more positive ASE variables than children in the lower SES groups. This was particularly true for social environmental factors, home availability of fruit and intention to eat fruit. MSEM showed that the relationships specified in the adapted ASE model were moderated by SES, as we did not find support for equal model structure across the three samples. Model modification for each SES group separately showed that the relation between home availability and fruit intake was not significant for the medium and low SES groups, and the relation between self-efficacy and intention to eat fruit was not significant for the medium SES group. Future interventions aiming at increasing fruit intake in children need to be sensitive to such SES-related differences and should in particular affect factors that may impede fruit intake in the lower SES groups.