Sidel's writings brought him to the attention of Bernard Lown, who then invited him to cofound Physicians for Social Responsibility in 1961.
Sidel returned to Brigham and completed his residency, after which he held two fellowships arranged for him by David D. Rutstein through Massachusetts General Hospital.
Sidel was also active in International Physicians for the Prevention of Nuclear War, succeeding Bernard Lown as co-president of the body.
[3] In 1991, Sidel chaired the Technical Advisory Committee of the Food Research and Action Center's Community Childhood Hunger Report.
"[10] His wife, Ruth Grossman Sidel, a professor of sociology at Hunter College and author of numerous books and articles about the impact of poverty on women and children, died in 2016.