A police officer, a paramedic and a mental health professional will be patrolling the streets of Chesterfield together on the seven busiest days for drinking and parties over Christmas.
The Police and Integrated Care Team trial could be extended if successful.
The team will use an ambulance service fast response car and serve as a secondary response team to incidents.
The idea is to help people with mental health problems receive appropriate care and, should incidents occur, stop them being detained inappropriately such as in a police cell.
Insp Steven Ball from Chesterfield Police said: “A large percentage of the people we deal with will have mental health problems but it won’t always be apparent to us what might be the best way to deal with them.
“Where we would perhaps take them into custody the team could steer us and say that’s not appropriate in this case, this person is already being seen at home, or they can make a referral to their mental health worker.”