Seattle Hempfest is an annual event in the city of Seattle, Washington advocating the legalization of cannabis. Vivian McPeak serves as the organization's executive director. Founded in 1991 as the Washington Hemp Expo, a self-described "humble gathering of stoners" attended by only 500 people, and renamed the following year as Hempfest, it has grown into a three-day annual political rally, concert, and arts and crafts fair with attendance typically over 100,000. Speakers have included Seattle city council member Nick Licata, actor/activist Woody Harrelson (2004), travel writer and TV host Rick Steves (2007), (2010), 2012 Green Party speaker Jill Stein, Dallas Cowboys center Mark Stepnoski (2003), and former chief of the Seattle Police Department Norm Stamper (2006). Hempfest has also in recent years attracted such well-known performers as Fishbone (2002), The Kottonmouth Kings (2004), Rehab (2006), and Pato Banton (2007) to its five stages spread throughout Myrtle Edwards Park and Elliott Bay Park, on Seattle's waterfront.

Cannabis culture describes a social atmosphere or series of associated social behaviors that depends heavily upon cannabis consumption, particularly as an entheogen, recreational drug and medicine.