A graduate of the University of Pennsylvania and the NYU School of Medicine, he completed a residency in Internal Medicine at The Hospital of the University of Pennsylvania and is Board Certified in Internal Medicine. In 1988 he became a Robert Wood Johnson Clinical Scholar at Yale where he also earned a MPH degree in chronic disease epidemiology and added qualification in Geriatric Medicine from the American Board of Internal Medicine. He spent four years on the Yale Faculty before coming to Cornell to lead the Geriatrics Program. 

Dr. Lachs's major area of interest is the disenfranchised elderly, and he has published widely in the areas of elder abuse and neglect, adult protective services, the measurement of functional status, ethics, and the financing of health care. He has lectured internationally on these topics. His many honors and awards include an American College of Physicians Teaching and Research Scholarship, a National Institute on Aging Academic Leadership Award, and a Paul Beeson Physician Faculty Scholarship (the country's preeminent career development award in aging). He is also the recipient of RO1 funding from the National Institute of Health to study the impact of crime on the physical and emotional health of older adults. Recently, he was asked to serve as an advisor for the World Health Organization on Elder Abuse.

In January of 2000, Dr. Lachs became the first director of the Cornell Center for Aging Research and Clinical Care (CARCC), a multidisciplinary group of scientists, clinicians, and educators who seek to speed scientific advances from bench to bedside, teach geriatric medicine to physicians-in-training at all levels, and create a trans-institutional community of gerontologists at Cornell.

His service to community and country includes membership on an Institute of Medicine Committee to address the training needs of health professionals in family violence, and participation in the AMA/ABA joint conference on family violence. He also sits on the Board of the American Federation for Aging Research.

Dr. Lachs's greatest passion is practicing and teaching geriatric medicine in the outpatient, hospital, long-term care, and house call setting. He maintains a practice at The Irving Sherwood Wright Center on Aging; a community based ambulatory care practice for older adults, which he founded with Dr. Ronald Adelman in 1998. A unique social experiment intended to provide seamless medical and supportive services for older people. The physical space at 1484 First Avenue also is home to the Burden Center for the Aging (a community service organization) and the Hebrew Home for the Aged's Elder Serve Program (a home care agency). He and Dr. Adelman also lead a student interest group in Geriatric Medicine at Cornell.

He and his wife Susan have three children and live in Weston, Connecticut.