Low high school graduation rates continue to be a challenge in American public education. The pressure to meet the demands of adequate yearly progress (AYP) under the No Child Left behind Act of 2001 has led to an achievement gap in student performance between science and other core subjects, namely English, math, and social studies, on the Georgia High School Graduation Test (GHSGT). GHSGT statistics have consistently reflected a lower science pass percentage compared with other core subjects on the test. The objective of this nonexperimental, quantitative study was to analyze teacher perceptions on reasons for student science underachievement on the GHSGT. A self-developed questionnaire based on Bloom's taxonomy model was administered to 115 high school core subject teachers of a single school district. Analyses of variance (ANOVA) and chi-square tests were used to test hypotheses. Results confirmed that teachers perceived that (a) students demonstrated a low rate of proficiency in science because science demands higher cognitive skills, (b) less emphasis was placed on science because it is a non-AYP indicator, and (c) making science an AYP indicator will optimize student science achievement. Based on results, recommendations were made to promote the integration of English, math, and social studies curriculum with science curriculum to enable students to transfer learned skills and information across subjects. The potential benefits of outcome of this study include (a) providing critical insight for policy makers and educational practitioners to understand the impact of science underachievement on graduation rates, and (b) raising student science achievement to improve graduation rates. The following are appended: (1) Comparative Performance between GHSGT Core Subjects for 8 Randomly Selected School Districts; (2) A Visual Model of Interactions between Variables; (3) Achievement Gap and Science Underachievement (AGSU) Questionnaire; and (4) Letter of Invitation to Participate in the Survey. (Contains 19 tables and 1 figure.)