Last year, A dam N aor and his girlfriend placed an ad on Craigslist inviting strangers to Thanksgiving dinner in their apartment in the West Village neighborhood of Manhattan.

“There was no prior research, it wasn’t a trend we wanted to be part of,” said Mr. Naor, 32, who works for Indeed, an employment search engine. “We were just talking about how we could give back and be part of a community.”

His family was in California. Hers is in Germany. “We wanted to extend an invite to anyone that is alone, widowed, or without family so that you can have a more social dinner and enjoyable holiday,” the ad read in part.

Within hours, they said, they started receiving responses. They communicated with four candidates, and extended an invitation to the two who seemed more forthcoming.