The purpose of this chapter is to provide an overview of the most common types of cancer treatment modalities and to describe the role of navigators on the multidisciplinary treatment team during these phases of care. Patients may receive just one phase of treatment, such as surgery, or may be transitioned through various phases of treatment such as chemotherapy, radiation, and targeted therapy. Each phase or treatment requires decision-making, and the navigator serves as a patient advocate and patient educator and promotes the patient’s active participation in the treatment decisions that are being made. Navigators also reassess the patient for any barriers to care; these barriers can change depending on the phase of treatment the patient is receiving at any given time. A description of multilevel barriers, and strategies to address those barriers, is provided. Tables are provided for ease of reference. Several case studies are presented to highlight the role of the navigator throughout treatment. Special attention is given to Native American cancer patients, as well as sexual and gender minorities, two populations often ignored in mainstream patient navigation literature.