This study examined the development of noncognitive skills in a sample of 4,769 Hispanic/Latino students as they went through middle school and the first year of high school using ACT Engage 6-9, an assessment designed to predict student outcomes by measuring students' behaviors and psychosocial attributes. The scales of Academic Discipline, Relationships with School Personnel, and Thinking before Acting were examined longitudinally through HLM analysis. The factors of gender and several indices of academic achievement were used to predict differences in students' starting scores and growth over time. All factors related to academic achievement were significantly related to differences in students' starting scores in 7th grade on all three scales. Mean scores in Academic Discipline and Relationships with School Personnel declined between 7th and 9th grades, but increased in Thinking before Acting. Some indices of academic achievement were also significantly related growth in all three models; as was gender in the scales of Relationships with School Personnel and Thinking before Acting. The results of this study are consistent with prior research and indicate that there is a significant relationship between academic indicators and noncognitive skills, and that this relationship influences how these skills develop over time. These findings underscore the importance of these skills and suggest that measuring noncognitive skills would provide insight into differences in individual academic achievement. [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.]