The National Council on Problem Gambling is holding its 25th annual meeting in Boston July 1-2, just as debate again heats up in the capital city for a measure that would legalize casino gaming in the Bay State.

The event will be co-hosted by Massachusetts Council on Compulsive Gambling, whose executive director, Marlene Warner, told the Boston Heraldthat more than 500 clinicians and researchers are expected to attend. She estimates 4 percent to 6 percent of the population are problem gamblers and it’s unclear whether problem gambling will rise if gambling expands. Thomas Larkin, president of United to Stop Slots in Massachusetts told theHeraldthat expansion doubles the number of problem gamblers within a 50-mile radius of a new casino, using data from the 1999 National Gambling Impact Study Commission report.

The NCPG conference, which will offer more than 75 presentations on a comprehensive range of problem gambling topics, comes as the Massachusetts legislature is set to revisit legalizing casinos in the state. According to published reports, Gov. Deval Patrick, House Speaker Thomas DeLeo and Senate President Therese Murray met earlier this month in an attempt to outline the terms of the bill. Each has expressed support for expanding gaming in the state as a way to address revenue shortfall and job creation. The meeting was seen as an effort to avoid sharp public disagreement on basic details of gaming expansion at the top levels of state government, which many observers felt both helped sink a measure that would have created three casinos and two slot parlors last summer, and crowd other pressing matters out from the legislative agenda.