Background: Oncology patient navigators help individuals overcome barriers to increase access to cancer screening, diagnosis, and timely treatment. This study, part of a randomized intervention trial investigating the efficacy of patient navigation in increasing colonoscopy completion, examined navigators' activities to ameliorate barriers to colonoscopy screening in a medically disadvantaged population. Methods: This study was conducted from 2012 through 2014 at Boston Medical Center. We analyzed navigator service delivery and survey data collected on 420 participants who were navigated for colonoscopy screening after randomization to this intervention. Key variables under investigation included barriers to colonoscopy, activities navigators undertook to reduce barriers, time navigators spent on each activity and per contact, and patient satisfaction with navigation services. Descriptive analysis assessed how navigators spent their time and examined what aspects of patient navigation were most valued by patients. Results: Navigators spent the most time assessing patient barriers/needs; facilitating appointment scheduling; reminding patients of appointments; educating patients about colorectal cancer, the importance of screening, and the colonoscopy preparation and procedures; and arranging transportation. Navigators spent an average of 44 minutes per patient. Patients valued the navigators, especially for providing emotional/peer support and explaining screening procedures and bowel preparation clearly. Conclusions: Our findings help clarify the role of the navigator in colonoscopy screening within a medically disadvantaged community. These findings may help further refine the navigator role in cancer screening and treatment programs as facilities strive to effectively and efficiently integrate navigation into their services.