The KW area is home to a number of festivals every year, and a lot more!

GrandSocial is a decent website that lists events in the city. For school events the best place is to check relevant Facebook pages (Engsoc, Feds, etc).

Nightshift

An annual nightly festival featuring pop-up and interactive art in public spaces. Similar to Nuit Blanche in Toronto. Held every year around October - November.

Ribfest & Craft Beer Show

An annual summer rib and beer festival in Kitchener. I think the title speaks for itself.

Oktoberfest

German & beer festival in Kitchener around October, and runs for a week. Also the second largest Octoberfest in the world.

Multicultural Festival

Summer Lights Festival

EverAfter Festival

An EDM festival. Happens around summer (June).

Open Streets Uptown Waterloo

Royal Medieval Faire

Meetups

Hackernest: A monthly tech social. With free beer.