Gender-affirming chest surgery (GCS), or transgender “top” surgery, is designed to reshape the chest. Transfemales typically undergo breast augmentation, and transmales typically undergo mastectomy and tissue modification to create a male-appearing chest. According to the World Professional Association for Transgender Health (WPATH) criteria, all patients desiring GCS surgery require documentation from a trained mental health professional prior to surgical consultation. Thorough preoperative planning includes patient history, physical examination, and discussion regarding surgical goals. Breast volume, shape, degree of ptosis, size and position of the nipple-areolar complex, and inframammary fold must be carefully considered preoperatively in order to choose the appropriate surgical technique. Options for transfemale augmentation include silicone versus saline implants placed in distinct planes relative to the pectoralis muscle through a variety of incisions. The techniques for transmale mastectomy attempt to balance easily disguised scar placement with the maintenance of nipple sensitivity to achieve a flatter, more masculine-appearing chest wall. For both transfemale and transmale patients, postoperative breast cancer screening is recommended given observed changes with hormone therapy on residual breast tissue. This chapter aims to familiarize readers with the key aspects of trans and gender-diverse (TGD) GCS surgery.