More than 150 bar staff in Cardiff are to be trained in how to help cut binge drinking and the trouble it causes.
Bar staff are being trained on how to handle difficult situations
They will have lessons in who they can and cannot serve as well as tips on how to head off alcohol-related violence.
The initiative is part of a community safety project which has seen the number of drink-fuelled injuries in the city cut by a fifth since 2002.
Organisers have warned that bars which break licensing laws could be fined or have their licences revoked.
The idea of giving bar staff specific advice on how to encourage responsible drinking - and catch out underage drinkers - was developed after researchers interviewed 800 people.
Issues covered on course
The law about alcohol and young people
Who can be refused drinks in licensed premises
Which drinks are controlled by law, how the strength of a drink is measured and what a unit of alcohol is
The circumstances which may lead to violence on licensed premises and how trouble can be prevented
How barpersons can help to promote social responsibility in the use of alcohol
How to act responsibly over 'happy hours'
Their findings suggest that alcohol-related problems in Cardiff city centre are caused by a small minority of drinkers.
Around 700 drinkers provided breath tests for the survey. Of these, 17 were three times over the drink-drive limit, while a quarter were within the limit.
The training, conducted by the British Institute of Inn-keeping Awarding Body, aims to reduce binge drinking and associated problems such as violence and anti-social behaviour.
The training aims to improve working practices to end the sale of alcohol to drunk or underage customers as well as to help bar staff when they are handling potentially difficult situations.
The initiative marks an intervention by the Lion's Breath research project, led by the Cardiff Community Safety Partnership and backed by police, Cardiff University and the Alcohol Education and Research Council.
Project chair, Professor Jonathan Shepherd, said: "One key aim is to attempt to improve the working practices of the city's licensees, which includes work around the mis-selling of alcohol to drunk or underage customers.
"Both acts are illegal and can result in a licensee being fined and losing his/her licence.
"This is not what we want to see, as Cardiff is largely a safe, vibrant and successful city.
"However, we are mindful that such alcohol sales can increase the level of danger faced by those being inappropriately served, other revellers and innocent bystanders who become the victims of alcohol-related violence."
Dr Simon Moore, from Cardiff University, said its surveys found "excessive drunkenness, disorder and aggression" were exhibited by a minority.
"The vast majority of people enjoy the city's pubs, clubs and restaurants and, on the whole, drink sensibly," he added.
Erica Painter, from the Cardiff Community Safety Partnership, said the interviews were helping to establish "a picture of Cardiff's night-time economy".
A South Wales Police spokesman added it was always looking for new ways to make Cardiff safer.