A police operation in June, involving shopkeepers and youth volunteers, uncovered 32 cases of so-called proxy purchasing and led to two arrests.
Police Scotland data suggested since then the number of people drinking in public places was reduced by 55%.
Officers also reported fewer complaints about youth-related disorder.
In Scotland, people face a fine of up to £5,000 or even a prison sentence for buying alcohol for people under 18.
The ‘You’re asking for it’ campaign is an effort involving the Scottish Alcohol Industry Partnership, Police Scotland and North Lanarkshire Community Safety Partnership.
Insp Alistair Anderson, of Police Scotland, told BBC Radio’s Good Morning Scotland programme the issue was known locally as “jump in”.