A key determinant of whether social movements achieve their policy goal is how many people protest. How many people protest is in turn partially determined by violence from protesters and state agents. Previous work finds mixed results for violence. This paper reconciles the mixed results for violence by distinguishing between the timing of repression and its severity: low levels of state repression increase protest size while high levels decrease it, conditional on preventative repression failing. It evaluates the role of violence by applying deep learning techniques to geolocated images shared on social media. Across more than 4,300 observations of twenty-four cities from five countries, we find that protester violence is always associated with subsequently smaller protests, while low (high) levels of state violence correlate with increased (decreased) protest size.