Nuclear receptors (NRs) are transcription factors actively involved in many aspects of human physiology and pathology, serving as sensors of stimuli, master regulators of downstream molecular events, and hubs governing complex gene regulatory networks. The importance of various members of the NR superfamily in cancer has led to substantial efforts to target them therapeutically. Notably, drugs that block the action of estrogen receptor (ER)α in patients with ERα+ breast cancer or the androgen receptor (AR) in patients with prostate cancer have provided remarkable improvements in survival. However, there is continuing need for novel drugs that target ERα or the AR owing to resistance to established drugs, and there are also promising opportunities for targeting other NRs in cancer. In this review, we provide an overview of NR-based drug discovery in cancer and related resistance mechanisms, focusing on novel strategies for targeting well-established NR targets, including ERα, the AR, the glucocorticoid receptor, and the progesterone receptor, as well as opportunities to target other NRs that are attracting interest in immuno-oncology, such as liver X receptors, retinoic acid-related orphan receptors, and farnesoid X receptors. Copyright © 2019 Endocrine Society.