Hundreds of urban planning, smart-growth and development mavens from around the country will converge today and tomorrow for a confab on behalf of America's neighborhoods.

"Reclaiming Vacant Properties," at the Omni William Penn Hotel, Downtown, is sponsored by the National Vacant Properties Campaign.

In addition to participating in sessions on redevelopment of brownfields, use of vacant land for affordable housing, nuisance abatement, marketing and greening strategies, the conferees will visit successful land-use developments, including SouthSide Works, which occupies a former brownfield, and several smaller lots that are growing bio-fuels instead of weeds.

For the flip side, they could visit Marlene Jackson's ongoing project on Dinwiddie Street in the Hill, where she has lived in a microcosm of vacancy for almost two decades.

There's investment in her neighborhood now, spottily, and she has always held out hope that new housing, a new Carnegie Library branch and some new retail on Centre Avenue would help steer interest toward the weedy lots full of debris and abandoned homes.

As a member of the Dinwiddie Community Alliance -- a former block watch group -- she calls the city's Bureau of Building Inspections regularly to report abuses of properties.

"They know my voice," she said with a resigned smile. "I don't even have to say my name. If a lot of people don't call behind me, I'm just seen as a disgruntled lady."

On Friday, she invited city building inspector Bob McPherson out for a walking tour of Wick, Dinwiddie and Lombard streets and Diaz Way. The intersection that Dinwiddie forms with Centre Avenue is a neighborhood hub, but aside from a row of six handsome stone townhouses built in the 1990s, most of the homes on Dinwiddie are vacant and gaping under the elements.

"Some are dead-end," meaning the owners can't be located, she said, "and some have owners because I've gone on the Internet and pulled up the county assessment site and found names.

"There were supposed to be six more [new houses] across the street" from the ones built in the '90s, she said. "That was going to be phase two" of a redevelopment plan between the city Urban Redevelopment Authority and the Hill District's community development corporation. But the vacant lots that were to have received new homes remain vacant.

"Last month, the Redd-up people [city workers] came and did some work," she said, "but the weeds have grown up again. I want a commitment that these properties will be maintained. We have houses that are open" and used by squatters. "We have lots that need to be cleaned, yards that need to be cut and owners that need to be cited to keep their property up. When you see something that's well manicured, with no debris, it helps your pride."

All the issues Ms. Jackson is dealing with are issues to be addressed at the conference.

"Cities all over the country face the challenges of demolition and ownership issues, environmental concerns, legal obstacles," said Ellen Kight, executive director of the Pittsburgh Partnership for Neighborhood Development. She said people who attend will go away with contacts for environmental, technical, legal and development assistance.

The National Vacant Properties Campaign, which has four sponsor funders, offers technical assistance to cities and builds a network of advocates and problem-solvers, said Jennifer Leonard, director of the campaign, in Washington, D.C.

About 120 speakers will be among an expected 550 people attending the conference, she said. Many are coming from other cities to present ideas and methods that have led to successful use of vacant property.

Individuals interested in attending may register at the Omni William Penn today between 7 a.m. and 5 p.m. or tomorrow between 7:30 and 8:30 a.m. Costs vary, from $425 for someone in the private sector to $325 for a nonprofit group representative and $75 for a student. Ms. Leonard said she has been offering the student price of $75 to senior citizens.

For more information, visit www.vacantproperties.org and click on the Reclaiming Vacant Properties logo, or contact the conference planner by calling the Omni William Penn at 412-281-7100.