The purpose of this study was to explore factors influencing middle school students' academic achievement. In this regard, the study investigated the impact of demographic factors and students' attitudes towards STEM on their achievement. The research sample was drawn from a city located in southeastern Turkey. Multiple regression analysis was carried out to predict how much each subscale of the STEM survey, along with some other predictors as control variables, can be used to estimate achievement. In this present work, the variable of parental education was found significant. Moreover, it was found that the number of siblings, the status of being seasonal agricultural workers, and preschool education are significant predictors, but gender and the possession of a computer at home are not significant predictors. It was further determined that the "learning of science and engineering and the relationship to STEM" sub-dimension of STEM significantly predicted achievement, but the "personal and social implications of STEM", "learning of mathematics and the relationship to STEM", and the "learning and use of technology" sub-dimensions are not significant predictors. The findings suggest that academic achievement and STEM outcomes are somewhat mutually related. Students' positive attitudes toward STEM are promising and indicate the importance of higher achievement.