The term prison library refers to libraries that provide educational, legal, recreational and other resources in correctional facilities throughout the globe. While their services are primarily oriented toward inmates, they may also serve other members of the prison community, such as the inmates' families and prison staff. Key differences that set a prison library apart from other types of library, such as public or academic, include the level of access to qualified library staff, skills required as a prison library worker, the level of censorship, reduced privacy, limited or no internet access and the goals of collections and library programming. The quality and nature of a prison library can vary based on the country, state, city, and individual institution. Prison libraries are often managed by a trained librarian, educator, clergy or prison personnel, but in some cases a single librarian may oversee the libraries of multiple institutions at once. Inmates may also work in prison libraries.

In the United States, reading materials are provided in almost all federal and state correctional facilities. Libraries in federal prisons are controlled by the Federal Bureau of Prisons, U.S. Department of Justice. State prison libraries are controlled by each state's own department of corrections. Many local jails also provide library services through partnerships with local public libraries and community organizations. These resources may be limited, mostly provided through government sources.

Role Prison libraries have an important role in serving currently incarcerated people by providing access to educational opportunities, promoting mental health and wellbeing, and fostering opportunities to cultivate family connection. Because of these opportunities, prison libraries in the research are reported to decrease likelihood of recidivism among reentry citizens.

Research shows a correlation between education and reduced recidivism, and libraries play an important role in supporting education.Marshall, A. M. J. (2011). Library services in correctional settings. Information Outlook, 15(1), p. 24–26 Many currently active prison libraries offer education through reading materials and literacy programs such as Hydebank Library where currently incarcerated people can practice reading aloud in the library, interact with one another through programming, and work on creative projects. In other correctional institutions, prisoners are sentenced to a literature discussion group in lieu of prison time. One such program called Changing Lives Through Literature (CLTL) has been operating since 1991. The first CLTL group in Massachusetts had a 19 percent recidivism rate as compared to 42 percent in a control group.Sussman, D. B. (2014). Reading Reduces Recidivism: Getting Books to Prison Libraries. ILA Reporter, 32(6), p. 7 Education allows inmates to obtain the skills they need to transition back into society once they are released, and libraries can play in an important role in helping inmates learn these skills. Some programs prison libraries offer include, GED instruction, literacy classes, life skills classes, typing instruction, and classes on how to use a library.Bookmobile Outreach Services, 10(2), p. 43–61.

In addition to educational opportunities, through various literacy skills programming and activities, prison libraries can play a role in building family relationships. For example, the Jessup Correctional Institute in Maryland started a program that provided books for prisoners to read to their children or grandchildren on visiting days.NPR. (2011). Prison library offers place to escape. Other prison libraries have programs in which prisoners record reading stories, and the tapes and books, along with a coloring book and crayons, are sent to their child.(Greenway, p. 54) Some inmates try to read the same materials their children are reading, so they have something to talk about with them.

Prison libraries provide a space for inmates to meet with others with common interests. Prison libraries' physical spaces can also provide comfort and support the mental wellbeing of currently incarcerated people. Though funding is limited, some prison librarians are diligent in providing programming. Such programs include book clubs and community service projects. Many inmates utilize the library as a means of escape from the reality of their current situations. One of the many services provided by a prison librarian is to have conversation with the inmates regarding the reasons they are in their current situation, after which, the librarian will make catalog suggestions to the inmate that will give them guidance in future decision making.

Challenges Funding and space are two major challenges for prison libraries.(Greenway, p. 55–56) Prison libraries are on the low end of budget priorities for prisons. It is difficult to provide up-to-date information and classes with a limited budget and space. Associated with limited budgets are time constraints. Some prison library staff feel they do not have the time to complete all of the tasks they need to because prison libraries are under­staffed.(Greenway, p. 56) By 2019, technological developments such as the choice to transition to tablet-based information access led to prison elimination of law libraries in South Dakota and has threatened to end book donations to prisoners and their libraries in favor of charging prisoners for books available in e-book format. Another challenge is the literacy of inmates. For example, in the United States, "seventy-five percent of the state prison population did not complete high school or are classified as low literate". Other challenges include security risks. Some librarians feel like they are guards and other libraries are monitored by correctional officers.(Greenway, p. 57) Finally, some libraries have to deal with damage and theft of items. Library staff may also be responsible for scanning books for contraband such as tobacco and betting cards, which can be considered a form of censorship.

A challenge in the development of prison libraries in the US came about in the Steven Hayes case, where library collection policies, and patron (prisoner) privacy came into question. It was suspected that Hayes' reading choices in his former prison "fueled his crimes". The prosecutors in his case wanted to see Hayes' reading lists after he was convicted of the murder, kidnapping and sexual assault of members of the Petit family. This issue is contentious because according to normal library policies, patron privacy is a very serious matter, and the question of whether it changes within a prison library was highly debated. Conrad does not mention that any real rulings and/or concrete decisions have been reached as there are strong arguments both for maintaining prisoners' privacy, as with any other patron, and there are arguments for that information to be made available to ensure that there is no danger to the prisoner, prison population or general public.

Censorship is another major challenge reported by prison libraries. The Federal Bureau of Prisons regulations state that publications can only be rejected if they are found to be "detrimental to the security, good order, or discipline of the institution or if it might facilitate criminal activity." However, prisons censor materials far beyond these guidelines. Restrictions on the content of materials in prison libraries are imposed by prison authorities such as wardens, administrators, and security personnel, resulting in the infringement on prisoners' right to read. "Both formal and informal processes of censorship occur in the prison, and there is significant variation in which materials are censored from one institution to the next." Typical topics that are censored include works mentioning violence, pornography, hate against a particular group crime, or instructions on how to commit crimes. Arguments against this kind of censorship include the observation that violence is present in most media, including the news. Conrad points out that while there are valid security concerns, like other libraries, prison libraries can protect intellectual freedom by building and maintaining appropriate collections development policies.

In another example of the conflict between safety and free access to information, many prisons only offer limited internet access to inmates or none at all. In lieu of direct internet access, inmates may be able to access resources such as educational videos, documents, and materials needed for remote classes using offline tools and databases or an internal network/prison intranet. In some cases, library professionals may have access to the internet even if their patrons do not in order to keep loan records, search for catalog items, or send emails among other functions.

International institutions At the international level, there are documents providing standards, and recommendations for how prison libraries should be run. These include Article 19 of the Universal Declaration of Human Rights (1948), the IFLA & UNESCO Joint Public Library Manifesto (1994), IFLA Guidelines for Library Service to Prisoners (first published in 1992 and last revised in 2005), and the United Nations Standard Minimum Rules for the Treatment of Prisoners (first established in 1955 and last updated in 2015), which also became known as the Nelson Mandela Rules in 2015. However, the extent to which these are actually applied varies by country, state, region, city, and individual institutions.

United States

America has had prison libraries since 1790. The first state prison library was established in 1802. At the beginning of the 19th century prisons were usually operated by the clergy. The purpose of the library was to increase religious devotion and modify behaviour. In many prisons during this time period the library collection consisted only of the Bible and sometimes prayer books. According to Lehmann (2011), "The main purpose of reading was believed to be strengthening of character, religious devotion, and what we today would call behavior modification. By the mid-nineteenth century, penology (the study, theory, and practice of prison management and criminal rehabilitation) had become more scientific, and criminologists claimed that they knew the reasons for criminal behavior and, consequently, how to reform criminals."

In 1870, during the Progressive Period and Prison Reform Movement, the Prison Congress began calling for rehabilitation of convicts instead of retribution, and education and rewards for good behaviour. The library was seen as an incentive and only contained items which furthered the reformative goals of the prison. The first manual for prison libraries was published by the American Library Association in 1915.

During the Great Depression prison libraries were expanded. With a decline in industrial demands prisoners became idle and restless and libraries were seen as a way to occupy them. In 1930, a manual for prison libraries was published by the American Correctional Association. The library was believed to be wholesome recreation, which also supported education and mental health, and there was great growth in federal prison libraries for the next four decades.