MARIETTA — Cobb County parents now have another reason to think twice before allowing their teenage children to have a party with alcohol in their homes.

With the 5-0 passage of a code amendment last week, Cobb joined communities in 24 other states to put a “social host” ordinance in place. The law provides penalties of $150 for a first offense and $500 for subsequent offenses for adults who host gatherings in which underage drinking takes place.

“Let’s say you’re a parent and you allow your kids to have a party, and you say ‘I’ll take up everybody’s car keys and everybody stays in the basement,’” Cobb County Community Development Director Rob Hosack said. “If there are any routine complaints, and law enforcement goes and notices people are drinking, not only do the kids get underage drinking tickets, the parents get tickets as well.”

Cathy Finck, coordinator of the Cobb Alcohol Task Force, said she was alarmed to see Cobb State Court statistics for a recent year that showed 1,309 minor-in-possession cases, but only 38 furnishing alcohol to minor cases. She said the new law will be easier to enforce than furnishing alcohol to a minor or contributing to the delinquency of a minor cases because the only burden of proof with the social host ordinance is that police issued a minor in possession citation.

The alcohol task force, a group of individuals and organizations that works to reduce underage drinking, studied several social host ordinances across the country. Ventura County, Calif., which Finck said has demographics similar to Cobb, was the first community to implement the laws.

“We have been working on it for quire a while,” she said. “It was critical because we knew that private house parties are the No. 1 source for alcohol.”

The law went into effect immediately upon approval by commissioners, Hosack said. During the public hearing process, the ordinance was changed to make sure that anyone who is cited must be in physical control of the location of the party. Concerns had been expressed about parents being ticketed even if they were out of town when drinking went on in their home.

At the July 24 Board of Commissioners meeting, speaker Craig Harfoot said it was hypocritical of the county to pass a law intended to make it more difficult for children to drink, while part of the same group of code amendment changes made it OK for alcohol to be served at private, after-hours functions at the Cobb Safety Village, where children are taught lessons about safety from fire and other dangers.