And they asked every single person, "Do you have a place to stay tonight?"
The survey, organized by the Douglas Mental Health University Institute Research Centre, along with partners including the YMCAs of Quebec, aims to get a better idea of how many people actually live on the street.
A census of the homeless population has been done in other North American cities, but never in Montreal.
"If you want to seriously tackle the issue of homelessness, you have to have a method for tracking the phenomenon over time," Eric Latimer, the McGill University researcher responsible for the survey, told CBC.
Volunteers interviewed people such as Victor Derry, who has been homeless more than 15 years. He said the survey was a good idea.
"It gives people a general idea of what being homeless is about," Derry said, though he was skeptical homelessness could be eradicated.
"There will always be somebody without a place to live because some people do not like society, and society does not like them. Basically they clash. That's all."
Volunteers will continue the count on Wednesday and Thursday night.
Lisa Marie Scolack, an outreach worker with the Saint Michael's Mission and one of the survey volunteers, said she's hopeful the census will shine light on the issue.
"With a number, it always helps people to be aware of the situation," Scolack told Daybreak.
"It allows us to say what are the resources we have right now, and what's working and what's not working,"
The City said it will take several weeks to compile the census data and analyze the results. The final report will be submitted before the summer.