Bruce Ettinger, MD, Senior Investigator Emeritus at the Division of Research for Kaiser Permanente Northern California, Clinical Professor Emeritus of Medicine and Radiology at the University of California San Francisco (UCSF), and a charter member of ASBMR, died at age 81 years on June 15, 2020, of a brief (non–COVID-19) illness. Bruce had retired from official academic duties in 2003 following a long and highly productive career as a Physician Scientist whose focus spanned multiple aspects of skeletal health, particularly as they related to osteoporosis and menopausal management. Bruce's research activities ranged broadly from studies of fracture epidemiology and approaches for predicting fracture risk to leadership roles in pivotal clinical trials. He was instrumental in establishing a Northern California regional BMD surveillance program at Kaiser Permanente and, in collaboration with Harry Genant, conducted volumetric bone density assessments using QCT. He developed a patient-friendly computer model to calculate fracture risk in women and evaluated multiple fracture risk calculators using large-scale population data. Working with UCSF colleagues Steve Cummings and Deborah Grady, Bruce established the efficacy of ultralow-dose treatments for postmenopausal women. Bruce's research center contributed importantly to pivotal clinical trials in osteoporosis therapeutics, including studies of estrogens, SERMs, bisphosphonates, and teriparatide. He led the study which first reported that raloxifene (Evista®) prevented fractures in postmenopausal women. His more than 200 papers appeared in frontline journals, including the JBMR. After retirement, Bruce continued his work in advancing clinical fracture risk prediction and spearheaded an important update of US fracture incidence rates, which became the reference standard for the US Fracture Risk Assessment Tool (FRAX®). During the last 10 years, he partnered with Joan Lo at the Kaiser Permanente Division of Research to characterize the epidemiology of atypical femur fractures and ethnic differences in skeletal health. Bruce was born in New York City, where he attended PS 134 and graduated from Jamaica High School in Queens. He completed undergraduate studies at Columbia University prior to matriculating at Harvard Medical School. Following graduation from Harvard in 1964, Bruce took his residency training in Internal Medicine at the Boston City Hospital's Harvard services. In 1966 he began a 2-year stint as Captain in the US Army Medical Corps, which sent him to Yokohama. Although Bruce was trained in Internal Medicine, his superior officer assigned him to serve as the base Pediatrician. While in Japan Bruce found excitement in many aspects of Japanese life and culture. He learned Japanese woodcraft, ceramics, calligraphy, and cooking—skills that he maintained for many years. Upon returning to the United States, Bruce completed Endocrine Fellowship training with Dr. Peter Forsham at UCSF, where he subsequently received an appointment as Assistant Professor. He initially began to study nephrolithiasis and mineral metabolism under the mentorship of Gilbert Gordan, but his interests soon migrated to skeletal effects of estrogen, menopause, and postmenopausal osteoporosis, which ultimately became his signature focus. In 1972, Bruce joined The Permanente Medical Group, where he practiced Internal Medicine and Endocrinology and became the Regional Chair of Endocrinology. He was a superb and dedicated teacher, known for his courteous and kind manner, possessed of an accessible and reassuring way to explain complex topics. Bruce continued to spearhead highly impactful research in skeletal health within Kaiser Permanente for the remainder of his career. Outside of work, Bruce nurtured several long-term interests. At age 10 years he discovered a passion for model airplane construction, producing (and flying) for the next 70 years a collection of diverse aircraft that would make Boeing proud. Several years ago he diversified to produce model ships, which he raced in Golden Gate Park as a member of the San Francisco Model Yacht Club. He was an avid gardener who constructed a redwood Japanese garden on his return from Japan, and he later created San Francisco's first organic rooftop vegetable garden, which thrives to this day. Bruce was a superb woodworker, fashioning sophisticated and beautiful furniture and toy cabinets for his grandchildren. Having learned to play from his mother, Bruce loved to play and teach mahjong. He was a constant presence at ASBMR's Annual Meeting, always an inseparable dyad with his loving wife, Vivian. In addition to Vivian, Bruce is survived by their daughter, Kate, his son Jon (& Jenifer) Ettinger, his daughter Jennifer (& Joe) Lucido, and his grandchildren: Celia, Laurel, Storm, Sidney, and Jack. We remember Bruce as a kind, witty, generous, and loving human being, whom we sorely miss. The peer review history for this article is available at https://publons.com/publon/10.1002/jbmr.4131.