David and Mary Thomson Collegiate Institute (sporadically known as David and Mary Thomson CI, DMTCI, DMT, D & M Thomson or Thomson) is a semestered English-language high school located in Scarborough, Ontario, Canada originally sanctioned by the Scarborough Board of Education until its merger with its successor board, the Toronto District School Board in 1998. Its motto is Nil Sine Magno Labore (Nothing without great effort).