Patient navigation (PN) effectively increases screening colonoscopy (SC) rates, a key to reducing deaths from colorectal cancer (CRC). Ethnic minority populations have disproportionately low SC rates and high CRC mortality rates and, therefore, especially stand to benefit from PN. Adapting the Health Belief Model as an explanatory model, the current analysis examined predictors of SC rates in two randomized studies that used PN to increase SC among 411 African American and 461 Latino/a patients at a large urban medical center. Speaking Spanish but not English (odds ratio (OR), 2.192; p < 0.005), having a higher income (OR, 1.218; p < 0.005), and scoring higher on the Pros of Colonoscopy scale (OR, 1.535; p = 0.023) independently predicted colonoscopy completion. Health education and PN programs that increase awareness of the benefits of getting a colonoscopy may encourage colonoscopy completion. In the context of language-appropriate PN programs for African American and Latino/a individuals, those with lower incomes and English speakers may require additional education and counseling to support their decision-making around colonoscopy.