He met Charles L. Todd while they were both working in the Department of Public Speaking at City College in the late 1930s.
In addition to doing ethnographic research with Todd in California, Sonkin also documented the African American community of the town of Gee's Bend, Alabama, where other Farm Security Administration (FSA) work was being carried out.
Like Todd, Sonkin was drafted into the military during World War II, where he served in the Army Signal Corps.
At the end of the war, Sonkin returned to City College and became professor of speech.
In 1977, collaborators Todd and Sonkin jointly published a biography of Alexander Bryan Johnson.