Violence is often measured in shootings and murder rates.  Gun violence in Philadelphia actually dropped in 2012, but a two-day conference starting Monday is focused on other ways it takes its toll.

"We know firsthand the emotional costs, the trauma that's associated with having to bury a son, daughter or loved one to violence," said Dorothy Johnson-Speight, founder of Mothers In Charge, the group hosting the violence prevention conference.

But, Johnson-Speight said, there are also costs that everyone bears, from prisons to emergency rooms.

"So we're having Dr. Dan Taylor, who's with St. Christopher's Hospital; we've having Police Commissioner Ramsey; we've having Prison Commissioner Louis Giorla; we're having many different people that are working on this issue every day because the cost is tremendous," he said.

In addition to discussing the costs of violence, conference participants hope to develop strategies that will make a difference, Johnson-Speight said. 

A discussion about the connection between behavioral health and violence will feature Dr. Arthur Evans, who heads Philadelphia's Department of Behavioral Health and Intellectual disAbility Services.

Traumatic stress and violence play major roles in the development of behavioral health conditions, according to Evans.

"What we're doing is getting into communities pretty quickly after these kinds of events, attending community vigils, educating people about what is a typical response to a traumatic event and then what is an atypical response to a traumatic event, and then how to get help," he said.

Evans said getting to people quickly after a traumatic event can help prevent substance abuse, depression and post-traumatic stress disorder.