Sex work, the consensual provision of sexual services for money or goods, is criminalized in most countries. Decriminalization is distinct from legalization (also known as the "regulationist" approach).

Advocates of decriminalization argue that removing the criminal sanctions surrounding sex work creates a safer environment for sex workers, and that it helps fight sex trafficking. Opponents of decriminalization argue that it will not prevent trafficking (or even increase trafficking) and could put sex workers at greater risk. Evidence from New Zealand, Belgium, and several Australian States (which have implemented this legal model) demonstrates that decriminalization is an evidence-based harm reduction approach.

Organizations including: the Joint United Nations Programme on HIV/AIDS (UNAIDS), the World Health Organization (WHO), Amnesty International, Human Rights Watch, United Nations Population Fund (UNFPA), and the medical journal The Lancet have called on countries to decriminalize sex work in the global effort to tackle the HIV/AIDS epidemic and ensure sex workers' access to health services. Almost all organisations run by sex workers themselves around the world favour the decriminalisation of sex work, and it tends to be their main goal. The Global Network of Sex Work Projects works with over 300 Sex Worker Organisations in 110 countries, all of whom are united on the goal of full decriminalisation and workers rights.

However, a European Parliament resolution adopted on 26 February 2014, regarding sexual exploitation and prostitution and its impact on gender equality states that, "decriminalising the sex industry in general and making procuring legal is not a solution to keeping vulnerable women and under-age females safe from violence and exploitation, but has the opposite effect and puts them in danger of a higher level of violence, while at the same time encouraging prostitution markets – and thus the number of women and under-age females suffering abuse – to grow."

Two countries have fully decriminalized sex work. In June 2003, New Zealand became the first country to decriminalize sex work, with the passage of the Prostitution Reform Act. The one remaining criminal law surrounding commercial sexual activities in New Zealand is a requirement to adopt safer sex practices, meaning condom usage is a legal standard. Despite decriminalisation, its sex industry is still controversial, with some issues remaining. In June 2022, Belgium became the first country in Europe and the second country in the world to decriminalize sex work. In 2024, Belgium added full workers rights for Sex Workers, including access to maternity leave, sick pay, health insurance, pensions etc. Several States in Australia have also decriminalised sex work, Queensland (2024), Victoria (2023) and Northern Territory (2019).

There are a wide variety of legal approaches to regulating prostitution. NGOs, academics, and government agencies typically use five different models to organize the different approaches. Scholars have also used three-fold and four-fold classifications, and terminology may differ between studies. Some may equate the term "criminalisation" with "prohibition(ism)", while others regard all policies except "decriminalisation" as a certain degree of criminalisation.

Hindle et al. (2008) stated: "Prohibitionism seeks to eliminate prostitution by criminalizing all aspects of the prostitution trade. Under this approach, prostitution is seen as a violation of human dignity. Criminal law and effective law enforcement are viewed as critical tools in reducing the number of individuals involved in prostitution." Kulick (2003) stated that prohibitionist models "criminalise the actual transaction of selling sex." Scoular (2015) noted that those taking a prohibitionist approach believe that the sex trade is a violation of moral (usually religious) beliefs, and seek "to deter parties from engaging in prostitution by punishing one (usually the female sellers) or, increasingly, both parties."

Hindle et al. (2008) stated: "Abolitionism is often described as the middle ground between prohibitionism and legalization. Advocates of this approach maintain that even though prostitutes may choose to enter the trade, it is nevertheless immoral. They believe that governments must take the necessary steps to allow prostitution to take place only as long as it does not infringe on public safety and order. Generally, abolitionists call for the criminalization of public solicitation." Kulick (2003) defined abolitionism as "a legal system that holds that prostitution in itself is not an offence, but the exploitation of the prostitution of others is; thus any third party recruiting, profiting from, or organising prostitutes is penalised."