The CMS Winter camp affords an opportunity for a small number of gifted secondary school students to work on competition-level mathematics as a group, under the supervision of a team of trainers. Fifteen students are invited to participate, based on their performance on mathematics competitions, and on the CMS correspondence training program. The camp takes place each January, and is part of the buildup to the IMO, which takes place over the summer. Many of the winter camp participants are candidates for inclusion on the IMO team, and some will attend the summer IMO training camp as well. But the winter camp is a stimulating and enriching experience for a larger group than the IMO team itself. It provides training early in the academic year, with the prospect in mind of influencing the students' achievement during the rest of the year.

The winter camp had rotated among a number of campuses for several years. Plans were made for it to return to York university, for an extended period of three years. Travel expenses of participants are covered by the CMS, and endowment grant support was sought to help with local expenses during this trial period. In the 2000 endowment grants competition, the Winter Camp was awarded $5000 in support per year, for each of the 2001, 2002, and 2003 camps. The camps are also supported financially by York University, through the Department of Mathematics and Statistics, the Dean of the Faculty of Pure and Applied Science, and Bethune College. The local organizer is Tom Salisbury, with the help of Ms. Anna Cavaliere and the staff of Bethune College (specifically, Ms. Suzanne Park, and Prof. Paul Delaney). Students work in three sessions a day - mornings, afternoons, and evenings - in a mix of lectures, problem solving sessions, and mock olympiads. Except for the final evening, when a banquet and end-of-camp celebration is organized.

The 2001 camp was held January 2 - January 7, 2001. Students and trainers stayed at Bethune College and Calumet College, on the York University main campus. Fifteen students participated, including four from Vancouver, one each from Edmonton, Calgary, and Ottawa, six from Toronto, and two from Windsor. The camp was directed by Waterloo's Chris Small (IMO team leader), with the help of Bill Sands (Calgary), Dorette Pronk (Dalhousie), Daryl Tingley (UNB), and Robert Morewood (Vancouver School Board). Other trainers present for at least part of the camp included Richard Hoshino (Waterloo), Ed Wang (Wilfrid Laurier), Tom Salisbury (York), Walter Whiteley (York), Franco Saliola (Cornell), Ed Barbeau (Toronto), and Valeria Pandelieva.

The 2002 camp was held January 3 - January 8, 2002. Students and trainers stayed at Bethune College and the adjoining Calumet College. A total of fifteen students attended, including three from Vancouver, one each from Edmonton, Calgary, London, and Montreal, four from Toronto, and four from Windsor. As team leader for the 2002 IMO, Arthur Baragar (Las Vegas) directed the camp, with the help of Bill Sands (Calgary) and Rob Morewood (Vancouver School Board). Richard Hoshino (Dalhousie), Neal Madras (York), Walter Whiteley (York), Valeria Pandelieva, Ed Barbeau (Toronto), and Naoki Sato all participated in one or more of the training sessions.

The 2003 camp was held January 3 - January 8, 2003. Students and trainers again stayed at Bethune College and Calumet College. The fifteen students participating came from Vancouver (1), Edmonton (1), Windsor (2), London (2), the Toronto area (7), Montreal (1), and Hillview Newfoundland (1). Andy Liu (Edmonton) directed the camp, and will lead the 2003 IMO team. Bill Sands (Calgary) helped organize the camp, and participated in the training. Tom Salisbury (York) made the local arrangements. Other trainers were Rob Morewood (Burnaby South Secondary School, and IMO team Leader Observer), Richard Hoshino (a Dalhousie University student, and IMO team Deputy Leader), and Lily Yen (Capilano College).