This research examined whether bilingualism would accelerate or hinder the cognitive as well as academic development of the Korean American individuals in an Oregon school district by analyzing the standardized test scores at grades 3, 5, 7, and 9. Eleven monolingual and 27 bilingual students released the Survey of Basic Skills (SBS) as well as Cognitive Abilities Test (CogAT) scores for this study. The analyses of the test scores revealed that the Korean-American students in this school district were performing at a much higher level against the national norm (the 50th percentile), or the school district norm (the 75th percentile). The bilingual Korean-American students made far greater progress both cognitively and academically from grades 3 to 9 (CogAT: 76.0 %ILE- 87.0 %ILE, SBS Composite: 77.0 %ILE- 87.0 %ILE) than their monolingual counterparts who hovered around the 85th percentile against the national norm. It was learned that the bilingual Korean-Americans were both cognitively and academically as developed as their monolingual counterparts by the time they were in 5th grade. Telephone interviews conducted with 46 bilingual and 23 monolingual Korean-American high school students as well as 30 written questionnaires returned by their parents revealed that the Korean-American students in this particular school district could not become naturally bilingual, but that a commitment both by the students and their parents was necessary to maintain their ethnic language. The parents of the bilingual students were making more efforts to pass on the Korean language to their offspring than the parents of monolingual students. The Korean-American families were very much integrated into the social mainstream, and were trying to achieve educational as well as economic successes on American's terms while maintaining their ethnic identity.