With Michael Medved (who later became a film critic), Wallechinsky was the co-author of What Really Happened to the Class of '65?, a series of interviews with their fellow high school graduates from Palisades High School in California ten years afterward. In the 1980s, Wallechinsky went on to follow with Midterm Report: The Class of '65: Chronicles of an American Generation.
He is the son of author and screenwriter Irving Wallace. When David was conducting genealogical research on his family, he discovered that the family's original last name was Wallechinsky. It had been anglicized to "Wallace" by an immigration clerk. He was so angered at this that he legally changed his name to "David Wallechinsky."
He has compiled the list of "The World’s 10 Worst Dictators" for Parade magazine for the last several years.