This quantitative, causal-comparative study examined the possible cause and effect relationship between educational programming, specifically one-way Spanish immersion and traditional English-only, and native English-speaking fifth graders' vocabulary and reading comprehension. Archival data was used to examine students' reading achievement as measured by the Iowa Assessment. Between-subjects multivariate analysis of variance (MANOVA) determined that no significant differences existed between the reading scores of students in the immersion and traditional program. Additionally, a one group pretest-posttest design was used to assess the growth of Spanish listening and speaking skills by students enrolled in the one-way Spanish immersion program using Language Assessment Skills Links Espanol (LAS Links Espanol). The results of dependent t-tests indicated that students made statistically significant gains in Spanish listening and speaking over time. [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/en-US/products/dissertations/individuals.shtml.]