Homelessness is a growing social problem plaguing Montreal and the entire country—yet the exact number of homeless people is unknown. Statistics Canada only tracks the number of residents of homeless shelters, enumerated during the census every five years.

That’s why the organizers of “I count MTL 2018” are calling for 1,200 volunteers to do a three-day count, and demographic survey, of Montreal’s homeless population. On the evening of Tuesday, April 24, volunteers will fan out in streets and parks across Montreal Island. During the daytime on April 25 and 26, they will visit community resource facilities that support homeless people.

It’s the second-ever Montreal-wide homeless count. The first count, conducted in March 2015, tallied 3,016 homeless people. Of those people, 429 were estimated to have slept outside. The other 2,587 were what are considered “sheltered homeless,” living in emergency shelters, transitional housing, hospitals, alcohol and drug therapy centers, or provincial prisons.