The authors' purpose was to examine the degree to which low achievement is related to ontogenetic factors (i.e., personal psychological traits expressed as attention and depression) or microsystemic factors (i.e., socioeconomic status, parenting, relationship with peers and teachers), using a total of 721 middle school students in South Korea. Based on the percentile rank, low-achieving students (bottom 15%; n = 323) and high-achieving students (top 15%; n = 398) were grouped, and a multigroup structural equation modeling was employed to determine which ecological factor(s) contribute to predict low achievement of middle school students. Results from multigroup structural equation modeling showed that 3 of the 6 ecological and ontological factors had significant direct or indirect effect on low achievement: socioeconomic status (direct effect), attention (direct effect), parenting (indirect effect). The findings are discussed in terms of the intertwined influences of ecological factors on low achievement, finally leading to the discussion on the limitations and future directions for research.