Cancer patients use complementary and alternative medicine (CAM) therapies at significantly higher rates (48%–69%) than the general population. To address this, many U.S. cancer centers have developed Integrative Oncology (IO) programs. The Society for Integrative Oncology (SIO) leads efforts to advance evidence-based, comprehensive integrative care for people affected by cancer. IO approaches include natural products (herbs, vitamins, minerals, probiotics), mind-body practices (yoga, meditation, acupuncture, tai chi, massage), and other complementary approaches (traditional Chinese medicine, Ayurveda, naturopathy, and functional medicine). SIO has produced multiple clinical practice guidelines, including major collaborations with ASCO for integrative pain management and supportive cancer care.