The objective of this study was to describe the selected conditions for school achievement of students with mild intellectual disabilities from Polish elementary schools. Participants were 605 students with mild disabilities from integrative, regular, and special schools, and their parents (N = 429). It was found that socioeconomic status (SES) was positively associated with child placement in integrative and regular schools rather than special schools, as well as with higher parental engagement in their children's studies. Parental engagement mediated the positive effects of SES and placement in regular and integrative schools on school achievement. The results are discussed in the context of inclusive education theory. (Contains 3 figures and 2 tables.)