Abstract: What explains the use of violence in extra-institutional political campaigns? Domestic groups challenge host states using both nonviolent and violent tactics. While Gandhi’s struggle for India’s independence is perhaps the most famous example of nonviolence, many of today’s bloody civil wars also started out as nonviolent movements. In a world eager to support the self-determination of marginalized groups, both nonviolent and violent groups receive support from foreign actors. Despite this, theories on the use of violence by these groups remain untested empirically.  This paper uses panel data to quantitatively investigate the proposition that external support of extra-institutional political movements causes an increase in the use of violence. A logistic regression model finds no statistically significant relationship between the provision of external support and an increased use of violence in primarily nonviolent campaigns. An additional test on a sample of violent non-state groups finds that battle-related deaths increased when external support was provided in the previous year, a result significant at 99% confidence.