In science education, there has been little research focused on indigenous students' achievement on science standardized tests when indigenous knowledge is integrated into the test questions. However, there has been an increased amount of research investigating the impact of culturally relevant curriculum adaptations on indigenous students' achievement in standardized assessments (Aikenhead, 1997, 2001b; Barnhardt, 2005b). This dissertation examines the achievement gap that is present between American Indian and White students in Montana. I use data from Montana eighth-grade standardized state science tests to determine whether incorporating indigenous material into classrooms and on state standardized science tests supported these initiatives and whether expected outcomes, such as a decrease in the achievement gap and in increase in Native student test scores, are being generated. Using a quantitative methodology, this study focuses on how American Indian students in Montana perform on standardized state science assessments when knowledge from a cultural curriculum, "Indian Education for All," has been included on the tests. Montana is the first state in the United States to use a culturally relevant curriculum in all schools and to create standardized test items based on this curriculum. This study compares White and American Indian students' test scores on these particular test items and overall test scores to determine the effectiveness of the culturally relevant educational initiatives implemented by Montana's Office of Public Instruction in terms of student achievement on state standardized tests. Results of this study uncover the persistence of an achievement gap, with Native students still underperforming when compared to their majority counterparts. American Indian students continue to score at the "nearing proficiency" level, which is one level lower than White students are scoring, at the proficient level. When scores are investigated for items written based on cultural standards, American Indian students tend to answer these items correctly a greater percentage of the time then they do other items; yet White students are answering these culture-specific items correctly a greater percentage of the time than are American Indian students. Understanding the connections between student achievement and an adapted, culturally relevant science curriculum brings valuable insights to the fields of science education, research on student assessments, and indigenous studies. Implications of the study are reflected in recommendations for (1) integrating culturally relevant test items in greater number on standardized science tests; (2) encouraging greater participation of community members in education; (3) encouraging greater participation of Native individuals in the test construction process; and (4) attending to the frequency of and teaching methodologies for implementing the "Indian Education for All" curriculum. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]