Hyams, TravisThe rates for colon and rectal cancer (CRC) are increasing at an alarming rate in individuals under the age of 50. Because of this, The American Cancer Society gave a qualified recommendation for average risk adults to initiate colorectal cancer screening at age 45. This recommendation challenges the long-standing guidelines to begin screening at age 50. If adopted, this would add approximately 19 million Americans to the eligible screening pool. This shift in thinking is controversial and researchers and guideline recommending organizations have responded with caution. While a large body of literature on CRC screening exists, very few studies have focused on individuals under the age of 50 due to the previous, relative consensus on guidelines. Because the uncertainty and relative equality of screening strategies and outcomes, patients under 50 and clinicians making decisions about screening should consider a shared decision-making framework. In this dissertation, I explored differences in several constructs of the shared decision-making framework by age (<50 & ≥50) using a sample of 579 participants drawn from MTurk, a global crowdsourcing workforce that is often utilized for research studies. In paper 1, I evaluated knowledge of CRC risk factors and symptoms and found that age moderated the relationships between several independent variables including perceived likelihood of getting cancer and numeracy with total knowledge scores. In paper 2, I explored preferences for colorectal cancer screening strategies using a multicriteria decision analysis technique called the Analytic Hierarchy Process and found that participants <50 preferred colonoscopy more often than those ≥50. In paper 3 I used multinomial logistic regression and found that participants <50 preferred the shared and passive role compared to the active role for deciding whether to get screened and deciding which strategy to use more often than participants ≥50. These findings will act as a foundation for future work if it becomes necessary to incorporate younger people into colorectal cancer screening programs.enDissertationBehavioral sciencesPublic healthColorectal cancerguidelinesscreening