This study evaluates the effect of attending a U.S. public middle or junior high school as compared with a K-8 school on eighth graders' academic and psychosocial outcomes. In a national sample, we conducted propensity score weighted regression analysis. Initial findings indicated that for eighth-grade students, attending a middle or junior high school negatively affected teacher- and self-reported reading/writing competence. After applying population weights, only reading self-concept remained negatively affected by middle school enrollment. Exploratory analysis revealed the negative effects of attending a middle grade school may be present only for the students who enter kindergarten not at risk as measured by socioeconomic status (SES) or academic performance. Taken together, results suggest that negative impacts of middle grade schooling may be limited to teacher- and self-reported reading/writing competence, more pronounced in middle versus junior high school, and more salient for less disadvantaged students. Implications for theory, policy, and practice are discussed.