Effective school administrators and teachers are those who provide the least restrictive learning environments for all students. The main goal of this study was to analyze the effects of inclusive science education on the general education population of middle school students' scientific conceptual understandings. The study was designed as a quasi-experimental model and conducted in a middle school in a large urban school district in Midwestern US. Approximately 4% of students in the school were receiving special education services. The participants in the study were selected through non-random selection. The participants of this study included 20 students without disabilities in each classroom with a total number of 120 students from a total of six different middle school classrooms. The study included two classrooms (one inclusive and one non-inclusive) for each grade level (6, 7, and 8). The conceptual change of students without disabilities was measured using the Density Assessment, which included 20 multiple choice questions. SPSS program was used for data analyses. Paired samples t-test and a multivariate group analysis test were conducted to investigate significant differences on students' conceptual understandings. The findings showed that the effect of inclusive education was significant and positive on the conceptual understanding of students without disabilities in inclusive science classrooms.