Gambling involves risking something of value (the “stakes”) on an event with an uncertain outcome, where the intention is to win something else of value. It includes a broad range of activities, from those that involve skill to those that require no skill, and it may take place on a small scale (e.g., a roll of the dice, or bets placed on individual sporting events) as well as large scale (e.g., the regulated national and provincial lotteries operated by many countries).

It is estimated that the total amount of money legally wagered on gambling events worldwide is approximately $10 trillion. This estimate does not include illegal gambling, which is much higher. Among the various forms of gambling, one that has received particular attention is betting on sports contests, which can be as simple as placing a wager on a single outcome, such as a particular game or individual player, to as complex as a whole season’s worth of games or entire competitions.

While gambling can be a harmless pastime for some people, it can also have serious consequences for others. Problem gambling can cause significant impairment and distress in a person’s life, resulting in loss of family relationships, work productivity, and/or personal finances. Some people can become addicted to gambling, and some are unable to stop. Problem gambling can lead to serious mental health problems, including depression and anxiety, and is often a consequence of untreated mood disorders.

Although the precise definition of gambling varies by jurisdiction, most agree that it involves a bet on the outcome of an event with an element of chance and the intent to win something of value. This definition excludes business transactions based on the law of contracts, such as a stock or bond purchase, and insurance payments, which are covered by laws regulating the business of insurance. However, it does allow for a distinction between gambling and other recreational activities such as playing card games or watching sports, which are not considered to be wagers on the outcome of an event.

There are a variety of treatments for gambling disorders, with most involving psychosocial interventions and medications. The most important step is recognition of a problem, which can be difficult for individuals to admit, especially if they have lost substantial amounts of money or have strained or broken relationships as a result of their gambling behavior. Those with the most severe gambling disorder are often recommended for inpatient or residential treatment.

Longitudinal studies provide the best opportunity to understand the onset, development, and maintenance of both normal and problem gambling behaviors. These studies can be conducted using a number of methodologies, but the longitudinal design is ideal for examining factors that moderate and exacerbate gambling participation, allowing researchers to infer causality. Unfortunately, the logistical and financial barriers to conducting such research remain formidable. Despite these challenges, longitudinal studies in gambling are increasingly commonplace, sophisticated, and theory driven. They can help identify the underlying factors that promote or deter gambling behavior and inform the development of new, more effective treatment interventions.