Approximately 57.7 million American adults experience diagnosable mental health disorders each year, but widespread stigma prevents many of them from seeking adequate help.

The City of Philadelphia — where one in four residents will be affected by a mental illness in 2014 — wants to spread awareness and offer support in a simple, inspiring way: by promising to listen.

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Tuesday, June 3 marks the first-ever #IWillListen Day, when Philadelphians can join a citywide conversation on mental health by pledging via social media to listen to others, without judgment. There will also be a health fair with various participating organizations taking place in the city's Love Park.

The event, which could eventually lead to a series of #IWillListen Days around the country, is a collaborative effort between the National Alliance on Mental Illness of New York City (NAMI NYC-Metro), the Philadelphia Department of Behavioral Health and Intellectual disAbility Services (DBHIDS) and the Scattergood Foundation.

"#IWillListen is based on the simple principle that by listening, we can begin to break down the barriers for people to access care, treatment and recovery," said Colleen Kane, who is NAMI NYC-Metro's development and communications director and is in charge of the campaign.

"Through listening, you are creating a safe space in your community in which friends and family actually feel comfortable to approach you about an issue they may have."

By using the #IWillListen hashtag, participants can turn Facebook, Instagram, Twitter and Vimeo into support networks. NAMI NYC-Metro will use an API to pull all of the campaign's content onto its website, creating an online community and allowing you to see who else in your network has gotten involved.

The original idea for the #IWillListen campaign, which NAMI NYC-Metro first launched in October 2013, was inspired by research that showed stigma kept many people from taking advantage of NAMI's free mental health services before it was too late.

"We just thought, 'Why can't people know about us beforehand? Why can't they get to use the services that we offer before things get difficult to deal with?'" Wendy Brennan, executive director of NAMI NYC-Metro, told Mashable.

After NAMI NYC-Metro's board president told DBHIDS Commissioner Arthur C. Evans and Scattergood Foundation's president, Joe Pyle, about the #IWillListen campaign, the three organizations worked together to get Philadelphia officials involved.

"The power of the #IWillListen campaign goes beyond the one in four who are directly impacted, and reaches out to the four in four. It is everybody's responsibility to really change the culture," Brennan said.

Since it's a national organization, NAMI hopes other cities will adopt an #IWillListen Day in the future. However, that requires on-the-ground leadership from people like Evans and Pyle, Brennan explained. Right now, NAMI NYC-Metro is in talks with the New York City Department of Health and Mental Hygiene for a similar event.

The ultimate goal of the campaign is to erase the artificial separation between physical and mental health. In the ideal situation, Brennan said, every kid in the world would get both a physical and mental health checkup during every routine doctor visit, paving the way for specialty care, if need be.

"We just really need to start normalizing mental illness, and definitely need to start talking about it," she said. "It can't be seen as this death sentence. It has to be seen as a medical condition that is very treatable."

For immediate help, contact the National Suicide Prevention Hotline: 1-800-273-TALK (8255). If you live outside the U.S., you can find the appropriate resources here.