The Cognitive Science option is open to all University of Waterloo students and may be taken in conjunction with an honours or general degree. You should have at least a 70% cumulative average in the undergraduate courses you have already taken.
You would normally select the option in 1st or 2nd year, after completing one of the required courses, preferably PHIL/PSYCH 256 - Introduction to Cognitive Science. It is also possible to select the option later, but satisfying all the requirements before you graduate can be a challenge.
Send the program director a transcript of your marks and a one-page letter explaining your interest in Cognitive Science.