The organization, widely praised by area drug prevention and treatment experts, is patterned after Alcoholics Anonymous and similarly based on a 12-step recovery program.
NA says it hosts 60,000 meetings a week in 129 countries, and meetings will be held hourly around the clock through Sunday at the Philadelphia Marriott Downtown.
Not only will recovering addicts globally be attending, but many in treatment locally and still battling addiction will attend as well. At least 40 area veterans, clean for one to two years, will be there.
"The purpose of the convention is to share those stories of going from depth and horror of addiction to unbelievable diversity of life that we have," Meyer said. "There's some kind of paradigm shift when we hear somebody tell their story. 'If they can do it, I can do it.' "
Many emotional moments are expected.
On Saturday evening, there will be a countdown among at least 10,000 addicts in the hall. The count will begin when those who have been clean for at least 50 years are asked to stand. Everyone will clap. Eventually, those who haven't used drugs for a year, a month and even a week will be asked to stand, to increasingly loud cheers of support from others in the hall.
Those sober for a week or less are asked to come to the stage and are given a copy of NA's basic text, including the 12 steps, the founding principles, and stories from recovering addicts around the world.
"We believe we can't keep what we have unless we give it away," said Jane Nickels, a NA spokeswoman. "Recovering people have to show the new people how to live this."
Sunday features the Unity Day Call. More than 60 gatherings of NA members in such places as Australia, Bhutan, Brazil, France, India, Iran and Iceland will call in to the convention hall. In addition, groups from 98 prisons around the United States will call in, with many giving a shout-out, such as, "Hi from San Quentin."
All the groups hooked in remotely, about 15,000, can hear the speeches and activity on the convention floor.
"Everyone has a sense of being connected to our worldwide fellowship," said Nickels. "There's not a dry eye in the house."
"I think the world of NA," added Gary Tennis, a former Philadelphia prosecutor and now secretary of the Pennsylvania Department of Drug and Alcohol Programs, who sat on one panel Friday.
"I feel like the best people I've ever met in the world are in recovery. They have extraordinary integrity. Take tremendous personal responsibility for themselves. They give back. I refer to them as walking prevention programs."
Panelists, however, said they are deeply concerned about soaring use of prescription drugs, especially among young people.
"Between North Carolina and New York, there is a national prescription drug epidemic," said Mike Harle, chief executive of Norristown-based Gaudenzia, the largest treatment provider in Pennsylvania.
"And I think it is embarrassing," he added. "I'm really distraught that we are creating a whole new generation of narcotic addicts and we're doing it with legal prescriptions. As a culture, we should be ashamed of it. We have made these drugs so available to so many people with really negative consequences."
Deni Carise, deputy chief clinical officer for CRC Health Group, the nation's largest treatment provider, said, "My biggest concern is the number of high schoolers and young adults that are getting involved in prescription opiates and then transfer very quickly over to heroin. This is true in the Northeast corridor."
Ken Dickinson, Gaudenzia's marketing director, and a former addict and pharmacist, said, "As of 2011, the number one accidental death in America is no longer auto, it is opiate overdose."
Dickinson also said many overdoses come from mixing heroin with an incredibly potent and powerful opiate, Fentanyl.
"As of June 30 in Pennsylvania," he said, "we had 50 deaths from the drug Fentanyl, and in most of those deaths, the person was using heroin."
He said the Fentanyl is "50 to 100 times the potency of heroin," and gives an extra kick to heroin, which isn't as powerful as the prescription drugs that addicts were taking. "The Fentanyl is what's causing the overdose," he said.
Experts said the range of treatments - medications, counseling, residential programs, and NA meetings - has never been better, yet with such potent and available prescription drugs, addiction is only rising.
Carise said that more than 22 million Americans are addicted to drugs or alcohol today, about the same number who are in recovery.
With the passage of the Affordable Care Act, access to drug treatment programs should increase.
"The good thing about Obamacare is treatment was written into the law, coverage must be provided for substance abuse," said Harle. "But the law doesn't say what that coverage is, what should be provided." He said that's being worked out now.
Those at the convention may not drink or do drugs anymore, but they enjoy their music. Entertainment includes seven performances, including The Family Stone and Styx.
The public can attend, but individuals must buy a registration for $99. The convention program can bee seen at www.na.org/wcna.
Contact Michael Vitez at email@example.com or 215-854-5639. On Twitter: @michaelvitez