The Chinese writing system has traditionally organized the typographic text vertically, with one square-shaped character placed on top of another. With the influence of globalization, an increasing number of reading materials have been presented in the Western horizontal format, including school textbooks for children in Taiwan. This study looked at the unique phenomenon of readers being exposed to both vertical and horizontal reading in Taiwan, and examined the implications of text orientation for children's reading experiences and development. I examined the effect of the two orientations in both single line and paragraph formats. Ninety-two second-grade students and 82 fifth-grade students from a public school in downtown Taipei, Taiwan, participated in this study. Children's reading accuracy, reading speed, subjective and objective comprehension levels, and reading preference were examined among the four designed formats: Vertical Paragraph, Horizontal Paragraph, Vertical Line, and Horizontal Line in a computer screen. The results found advantages in horizontal reading for second graders in both reading performance and children's format preference. However, such advantages diminished by the fifth grade. The majority of fifth graders favored the Vertical Paragraph format and did not perform better with horizontal reading. A trade-off effect was also observed between reading performance and young readers' preference when choosing between the multiple-line paragraph formats and the single line formats. Second graders and low-level readers read slower and comprehended significantly worse in the two single-line formats--and the self-evaluation report showed their awareness of this fact. However, those less-skilled readers were more likely than skilled-readers to prefer the single lines regardless of the low performance and low self-evaluation. The results of this study offer implications for the design of recently released electronic reading devices. [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.]