Children's health is an important factor that influences their success in education--poor health, especially when induced by disease, has been linked to poorer cognitive performance, particularly among children across the developing world (Behrman, 1996; UNESCO, 2008; Jukes et al., 2008). One health concern, particularly for sub-Saharan Africa, that has been shown to limit children's cognitive functioning is malaria, a disease whose cognitive effects can be mitigated via mass anti-malaria treatment, also known as "intermittent preventative treatment" (IPT). In my dissertation, I analyze data from a cohort of 916 Kenyan adolescents, aged 11-16, participating in a cluster randomized trial of a school-based IPT program and examine how the cognitive growth rates--as measured on two tests of sustained attention--of particular subgroups of adolescents with and at risk of malaria differ in response to IPT. I also estimate the impact of receiving a specific dosage amount of IPT on their cognitive functioning. Based on my analyses using multilevel growth modeling, I find that adolescents who were randomly offered IPT experience faster cognitive growth rates than their peers who were offered a placebo; moreover, adolescents harboring a parasitic infection at baseline, "S. mansoni," experience the fastest cognitive growth. My findings based on the method of instrumental variables (IV) reveal that the cognitive functioning of children who receive a total of seven or more (up to nine) doses of IPT is significantly higher than their peers who receive six or fewer doses. In addition, adolescents with "S. mansoni" at baseline and treated with seven or more IPT doses have cognitive scores that are higher than their peers without "S. mansoni." Overall, my analyses show that IPT can significantly improve the sustained attention of adolescents who face potential detriments in their cognitive functioning due to malaria and malaria-related diseases. In particular, adolescents who have "S. mansoni' at baseline experience the largest overall cognitive gains from IPT. By improving adolescents' sustained attention, they may have an enhanced capacity for learning which can have consequences for the overall livelihood that may extend well into their futures. [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.]