Stalking is not a mental illness. It is a pattern of behavior, not a psychiatric diagnosis, and it does not appear anywhere in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), which is the standard reference clinicians use to classify mental health conditions. That said, the relationship between stalking and mental illness is more complicated than a simple no. Research suggests that between 50% and 75% of stalkers who enter the criminal justice system have some form of diagnosable mental disorder. But many do not, and having a mental illness does not make someone a stalker.
Why Stalking Isn’t a Diagnosis
Stalking is defined legally, not clinically. The National Institute of Justice defines it as a repeated course of conduct directed at a specific person, including physical proximity, unwanted communication, or threats, that would cause a reasonable person to feel fear. This can include following someone, leaving unwanted gifts, damaging property, spreading rumors, or harassing someone online. All 50 U.S. states have anti-stalking laws.
Clinicians, by contrast, don’t treat “stalking” the way they’d treat depression or schizophrenia. There’s no single psychological profile that produces stalking behavior. Instead, stalking can arise from very different motivations, personality structures, and mental states. Some stalkers are delusional. Others are calculating. Some are heartbroken ex-partners who can’t let go. Others are strangers fixated on a celebrity. Because the behavior can spring from such different psychological roots, it resists being packaged into one diagnosis.
How Common Stalking Actually Is
Stalking affects far more people than most realize. CDC survey data from 2023/2024 estimates that about 1 in 20 women (roughly 7 million) and 1 in 33 men (roughly 3.7 million) in the United States were stalked in just a single 12-month period. Those numbers make it clear that stalking is not a rare behavior confined to people with severe psychiatric conditions. It is widespread, and the people who do it come from a broad cross-section of the population.
Mental Disorders Linked to Stalking
While stalking itself isn’t a mental illness, mental illness is overrepresented among people who stalk. Research from the U.S. and Australia on stalkers in the criminal justice system found that the most common diagnoses are personality disorders, schizophrenia and other psychotic disorders, depression, and substance use disorders.
Borderline personality disorder (BPD) stands out in the research, particularly among female stalkers. One study of female stalking offenders found BPD was the most common personality disorder diagnosis. The core features of BPD, including intense fear of abandonment, emotional instability, and difficulty tolerating the end of relationships, can fuel the obsessive pursuit that characterizes stalking. Many of these individuals also had histories of sexual or physical abuse, which may have contributed to the development of those personality traits in the first place. Common motivations included anger, feelings of abandonment, loneliness, dependency, and obsession.
Erotomania is another condition strongly tied to stalking, especially stalking of strangers and celebrities. It’s a delusional disorder in which a person becomes convinced that someone else, often a public figure or someone of higher social status, is secretly in love with them. The person with erotomania isn’t just infatuated; they genuinely believe the other person initiated the romantic connection. They may interpret neutral or even dismissive behavior as coded declarations of love. This delusion drives persistent attempts to contact the object of their fixation, and it is recognized as a formal diagnosis in the DSM-5 under delusional disorder, erotomanic subtype.
Five Types of Stalkers
One of the most widely used frameworks for understanding stalking comes from researchers Paul Mullen, Michele Pathé, and Rosemary Purcell, who categorized stalkers into five types based on their motivation and the context in which the stalking began. These categories help explain why no single psychiatric label fits all stalkers.
- Rejected stalkers emerge from the end of a relationship. Their goal is either to win the person back or to punish them for leaving. This is the most common type, and many of these individuals have no diagnosable mental illness at all.
- Resentful stalkers are driven by a desire for revenge. They feel they’ve been wronged or mistreated, and the stalking gives them a sense of power and control through the fear they create in the victim.
- Intimacy-seeking stalkers want to establish an emotional bond and a loving relationship with the victim. They often believe, sometimes delusionally, that a deep connection already exists. Erotomania frequently appears in this group.
- Incompetent suitors are less focused on love and more interested in securing a date or short-term sexual relationship. They tend to lack social skills and don’t recognize that their attention is unwanted. Their behavior is often clumsy rather than threatening, but it still causes real distress.
- Predatory stalkers stalk as a means to an end, typically sexual gratification. They may engage in voyeurism or use the stalking period to gather information about a victim before an assault. This group is the most dangerous in terms of physical violence risk.
These categories make it clear that stalking serves different psychological functions for different people. A rejected ex-partner operating out of grief and anger is a fundamentally different situation from a predatory stalker planning an assault, even though both are legally committing the same offense.
The Distinction That Matters
The question of whether stalking is a mental illness matters because the answer shapes how people think about responsibility. If stalking were a mental illness, it would be easier to frame stalkers as sick rather than accountable. In reality, stalking is a choice, even when mental illness is part of the picture. Psychotic delusions can drive someone to stalk, but the majority of people with schizophrenia or delusional disorders never stalk anyone. Depression and personality disorders are common in the general population, and the vast majority of people with these conditions do not engage in stalking.
Mental illness can be a contributing factor, a risk factor, or a context that makes stalking more likely in certain individuals. But it is not the cause of stalking in most cases, and it is never an excuse. The legal system treats stalking as a criminal act regardless of the perpetrator’s mental health status, and the clinical world treats the underlying conditions (when they exist) rather than the stalking behavior itself.