An Institute is an asylum for Shadowhunters, and in some cases Downworlders and mundanes under their protection, and a safe house meant to lodge and assist Nephilim from around the world in their quest to kill demons. They are found in every major city across the world and are often located in churches or built on holy ground. Every Institute is run by a Shadowhunter or a pair of Shadowhunters with the position of head or co-heads of the Institute, respectively.
Institutes serve as the local power bases of the Nephilim, functioning like the embassies of mundane governments. They are the authority force of all the Nephilim in the city in which they reside and they oversee all tactical missions.
Institutes also serve as symbols of the power and sanctity of the Nephilim, standing as monuments to the Angel and glorification of their mission. Institutes are Nephilim homes, as much as Idris itself is, though Shadowhunters and members of a certain region's Clave branch have their own homes in the area and rarely stay at the Institute, aside from the heads, its wards and its occasional guests. The corollary to this is that Institutes are the responsibility of all Shadowhunters, not just the Shadowhunters who are stationed at a particular Institute or who are a part of the Conclave, or Enclave, of that Institute's region.
Orphaned Shadowhunters, or those whose parents have left the Clave, or have no residence in the area, are brought into the care of Institutes to be watched, raised, and trained as wards. They are usually trained in small groups, until they are eighteen, when they can decide what they want to do.
Once Shadowhunters turn eighteen, it is tradition to take a travel year and spend time in residence at an Institute well away from their home to allow them to learn the great variation in local Shadowhunter cultures, both in philosophy and in specific techniques, from a wide range of sources.
An Institute is a place for Shadowhunters to find safety in the event of danger. It is a stronghold for the Shadowhunters that live there.
While mundanes are not allowed into Institutes under normal circumstances, the Law allows for Shadowhunters to offer mundanes sanctuary if they are in imminent danger from any demon or Downworlder-related attack, as long as the situation does not compromise the secrecy and safety of the Shadow World.
The same holds true for Downworlders, who may also be hosted or held in the Institute for shelter, interrogations, meetings, or for the simple maintenance of their cordial relations, particularly those who assist the Nephilim. Since vampires cannot enter the hallowed ground of the Institutes, they are accommodated at the Sanctuary, which also contains holding cells for demons being interrogated.
Those guilty of minor violations are also sometimes held in the keeps of Institutes.
There was also a time when having Sighted mundanes as servants and caretakers in Institutes was a normal practice, usually generations or whole families of these mundanes, spread out across the world. This is less common nowadays.
An Institute belongs to the Council. Its guardians, appointed by the Clave, may live there, but it isn't actually theirs. They report directly to Idris. Therefore, it is considered unprofessional to decorate an Institute as one would a family home. The halls and public rooms should be kept clean of all family portraits. Institutes aren't supposed to be passed down from generation to generation. When the former head of an Institute dies, a new one is to be appointed without being a member of the former's family; the change of hand allows new ideas to enter seats of power. A good example of an unprofessional Institute would be the York Institute in 1878, when the Starkweathers, who had been running the Institute for centuries, decorated it like a family home.
The Consul, the highest appointed official in the Clave, is also a consulting mentor for the heads of Institutes.
All local Shadowhunters will be called to their Institute for Enclave meetings, to discuss local affairs that need not involve the Clave or Council. In some parts of the world, the head of the local Enclave is always the head of the largest local Institute; in some places they are different persons. Local traditions and history dominate; the only requirement is that the region be adequately represented in the Clave, however the local organization is structured.
To become the head of an Institute, a Shadowhunter must perform a ceremony where they are sworn in as such. They have to hold the Mortal Sword and answer the questions from the book of the laws of investiture, asked by the Inquisitor. These questions are law and never change. 
Being head of an Institute indicates a great deal of power. Though most Shadowhunters are paid roughly the same, Institute heads are paid more because of their difficult position. They deal with many administrative tasks: communicating with Idris, Downworlder negotiations, etc. Therefore, they are rarely seen going out on basic hunting missions and generally take on the more dangerous missions.
In the past it was not well seen for a woman to run an Institute if it was not in the company of her husband, but over time the job has become more egalitarian and nowadays there are as many women with the position of heads of Institutes as there are men.
Institutes do not have keyed locks. Instead any Shadowhunter may gain entrance to any Institute by putting her hand to the door and requesting entrance in the name of the Clave and the Angel Raziel.
There are some features common to all Institutes. They are built on hallowed ground and are heavily warded, constructed to repel demons and to prevent the unhallowed, particularly vampires, from entering. Their doors remain locked to anyone lacking Nephilim blood, and open to those possessing it. Materials with certain elements or magical properties are also used in its construction: the mortar for the buildings' stones are mixed with the blood of Shadowhunters, that in and of itself being a powerful protection, the wooden beams are of rowan, used to ward off malevolent spirits and enchantments, and for its density and strength, and the nails and metal rods are of silver and iron, protecting against werewolves and faeries respectively, or electrum.
Typically, and especially in well-populated areas, Institutes are glamoured to blend in with their surroundings. This glamour is usually chosen to make the Institute look not only ordinary but unappealing to visitors. For instance, the Institute of New York City, though in truth a magnificent Gothic-style cathedral, is glamoured to appear as a broken-down, boarded-up church, a derelict awaiting demolition.
Institutes are also protected by wards—"magical walls" that protect against demons. Although the wards of the demon towers of Alicante prevent electricity and similar power sources from working reliably inside its borders, the weaker wards of Institutes typically do not cause this problem. Most Institutes today are wired for electricity, or at worst gaslight, although witchlight is often used for atmospheric effect or as a backup in places where electrical supply may be unreliable. There are exceptions, of course—a few of the Institutes in more historically besieged areas, or more remote locations, are either too warded or too far from mundane civilization to use modern power sources.
Aside from these commonalities, one can find Institutes of all shapes and sizes, from the single-story sprawling villa of the Mexico City Instituto to the Eastern Carpathian Mountains fortress Institut high above Cluj in Romania.
Often, Institutes include architectural elements meant to evoke well-known buildings in Alicante.
Each continent has an Institute that contains the Great Library for that region of the world; each of these is the largest Institute on its respective continent. Often with these libraries are galleries showing the glory of that Institute, if there is no separate room for it. Spoils, at least those which have yet to be returned after it was made illegal, were kept and placed on display as historical curiosities.
Each of these larger Institutes has the capacity to house hundreds of Shadowhunters, although most Shadowhunters do not permanently live in an Institute. Normally, even the largest of Institutes has only a small number of permanent residents, who are responsible for maintaining the premises and equipment.
Institutes also have a weapons room and a training room. Shadowhunters are at liberty to enter the training room and develop their fighting skills at any given time. There are usually beams along the ceiling to allow Shadowhunters to practice flips, and a locker room attached to the training room for the Shadowhunters to store spare clothes while they train.
Institutes should generally always be well-stocked with a selection of varieties of weapons, from bows to seraph blades, made of all kinds of materials chosen for their magical properties, in addition to other basic useful combat tools such as: binding wire of silver, gold, and/or electrum; wooden stakes in oak and ash; amulets of protection; assorted holy symbols for major world religions; and basic magic implements (chalk, iron filings, small vial of animal blood, etc.). A truly well-stocked large Institute might add to that list such specialty items as lead swords, holy trumpets, bone staves, etc., depending on location.
Each Institute also has basic amenities to tend to the needs of its inhabitants. They have a considerably large and well-put together kitchen, and a formal dining room, able to seat over two hundred comfortably. Additionally, there are around two hundred bedrooms in the residential wings, open to Shadowhunters and others who wish to take up residence there. They all have infirmaries for healing injured Shadowhunters.
Most Institutes built before the 1960s contain Sanctuaries—unholy spaces purposely built outside the hallowed ground of the Institute to accommodate Downworlders, specifically vampires, and demons. When projection magic was invented by warlocks in 1958, the need for Sanctuaries obviated as most vampires would simply project themselves if the need to communicate with residents of the Institute arose. Most Institutes, however, predate that year, and their Sanctuaries have been maintained as contingencies and out of historical interest.
Initially, there were few enough Shadowhunters to not need any other place to flock to other than Alicante, which was where most of them were close to even years after their creation. Eventually though, Institutes were built to accommodate the increasing number of Shadowhunters and their globalization, and to meet the necessity for outposts and places of angelic power where Shadowhunters could organize and remain safe.
There are tales about the first Institute on the British Isles, in Cornwall, where the first Nephilim arriving with the Cup were believed to be wielding the Holy Grail, and whose tales of bravery and vigor have become mixed up with the mundane folklore of the isles.
- Baghdad Institute
- Bangkok Institute
- Barcelona Institute
- Beijing Institute
- Previously run by Jia Penhallow
- Berlin Institute
- Brussels Institute
- Budapest Institute
- Previously run by Lazlo Balogh
- Buenos Aires Institute
- Run by Joaquín Acosta Romero
- Cairo Institute
- The largest Institute in Africa
- Cardiff Institute
- An Institute that reports to the London Institute
- Cluj Institute
- Copenhagen Institute
- Cornwall Institute
- Previously run by the Blackthorns
- An Institute near Tintagel that reports to the London Institute
- Cyprus Institute
- Dublin Institute
- The Institute Bridget Daly came from
- Edinburgh Institute
- An Institute that reports to the London Institute
- Frankfurt am Main Institute
- Where the first edition of the Shadowhunter's Codex was printed
- Geneva Institute
- Istanbul Institute
- Kyoto Insitute
- Lahore Institute
- Lagos Insitute
- The Institute Rayan Maduabuchi came from
- Lisbon Institute
- London Institute
- Los Angeles Institute
- Madrid Institute
- The Institute Gideon visited to learn about different Shadowhunter cultures
- Manila Institute
- The largest Institute in Oceania
- Marrakech Institute
- Marseilles Institute
- Melbourne Institute
- Run by Christopher Makepeace
- Mexico City Institute
- Run by Carmen Delgado Mendoza
- Moscow Institute
- Mumbai Institute
- AKA Bombay Institute; run by Nasreen Chaudhury
- New York Institute
- Oslo Institute
- Paris Institute
- Run by Élodie Verlac
- Prague Institute
- Reykjavík Institute
- Rio de Janeiro Institute
- Run by Morena Pedroso
- Rome Institute
- Run by Chiara Malatesta
- Shanghai Institute
- São Paulo Institute
- The largest Institute in South America; run by Luana Carvalho
- Stockholm Institute
- Previously run by Oskar Lindquist
- Taipei Institute
- Tokyo Institute
- Vatican City Institute
- York Institute
- Run by Starkweather family until 1878
- According to Clary's note in her copy of the Shadowhunter's Codex, Luke told her that an Institute in Germany was actually a spoil taken from vampires and that it is still being fought over.