Several jurisdictions supplement the traditional response services provided by fire, EMS, and police with teams of behavioral health specialists trained to address issues concerning mental health crises, substance use, and related challenges. These programs fall into two broad categories, distinguished by whether behavioral health specialists accompany police officers, which is referred to as co-response, or act independently of police officers, called alternative response. Some jurisdictions combine the two strategies, depending on the perceived risk associated with response to a specific call. Here, we consider the characteristics of each approach and zoom in on several real-world models.


Co-response models couple a non-police practitioner, such as a social worker, mental health specialist, or other related professional, with a police officer. Together, they respond jointly to incidents and typically ride together during shifts.

The continuing participation of an armed officer comes with both advantages and disadvantages. On the one hand, co-responders can be dispatched to a wider range of calls, including those that may pose a safety risk (e.g., a weapon is present or a history of violence by the individual). On the other hand, a co-response model may fail to avert the harms that can follow from the unnecessary or excessive use of police.

Alternative Response

Alternative response models fully replace a traditional police response with non-enforcement practitioners. These responders typically are social workers, behavioral health clinicians, or paramedics, with a particular focus on stabilizing individuals in crisis. Teams are dispatched to calls that are determined not to pose a safety risk, though they are able to request officer back up if necessary.

In completely substituting officers with unarmed professionals, alternative response models are able to avoid the most serious harms associated with overuse of police and to free up officers’ time to respond to calls for which they are best suited and trained.

Real World Models

Denver, Colorado

The Co-Responder Program pairs a mental health specialist with an officer to respond to calls concerning individuals in crisis who may be experiencing a mental health or substance use problem. With an officer at the scene, co-responders can respond to calls that may involve the presence of weapons or threatening behavior. The co-responders are located within the Denver Police Department’s Crisis Intervention and Response Unit (CIRU) and have operated since 2016 in partnership with a local mental health agency. In that time, officer and behavioral health practitioner teams have responded to more than 10,000 calls, 98 percent of which have not resulted in arrest.

Support Team Assisted Response (STAR) deploys non-police responders to low-risk 911 calls regarding mental health, substance abuse, homelessness, and other related issues. The STAR team consists of a mental health clinician and a paramedic or emergency medical technician. Staff are unarmed, dressed in plain clothes, drive in a non-police van, and are trained to de-escalate issues and provide a harm reduction approach in their response to non-violent calls. They also provide medical triage resources, transportation, and follow-up service navigation to individuals in need. Recent research demonstrates that STAR reduced reports of low-level crime by 34% in the neighborhoods it patrols and is more cost effective than sending police.

Albuquerque, New Mexico

Mobile Crisis Teams (MCT) respond to mental and behavioral health emergencies by pairing a licensed mental health specialist and police officer. Six vans operate within the city and are dispatched directly through the 911 system. In its first three years of operation, MCT responded to more than 6,000 calls on issues such as suicide attempts and welfare checks.

Behavioral Health Responders are pairs of non-police first responders that are dispatched to community problems related to homelessness, substance use, mental health, public intoxication, and other social issues. These professionals have experience in social work, mental health, or social services, and are able to stabilize a crisis and navigate individuals to long-term services.