Specialists

§ When a City is first founded, all of its citizens are bound in the various requirements of day-to-day survival: hunting, fishing, tilling the land, and so forth. This may continue for some time, but eventually the city may grow large and prosperous enough that it can afford to dedicate some of its population to more rewarding pursuits. In Civilization IV, these more useful citizens are called "Specialists."
§ There are six categories of specialists in Civilization IV: Engineer, Merchant, Scientist, Artist, Priest, and the default "Citizen" specialist. Each provides a city certain benefits.
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Requirements for Employing Specialists

§ At the start of the game, you may only create one kind of specialist: the Citizen, who is the least useful of all of them. Each of the other specialist types requires certain Buildings or Wonders to be created. Further, each building or wonder will allow a limited number of specialists. For example, building a Temple allows you to create one (and only one) Priest in its city. But if you subsequently build a Cathedral there, you can create an additional two priests, for a total of three.
§ The Caste System civic allows you to create as many Merchant, Scientist, and Artist specialists in a city as you desire, regardless of whether or not you have the buildings that would normally be needed to create them. Be aware, however, that there is no way to get around the limitation on the number of Engineers and Priests that a city can support; you must have either the buildings or wonders necessary to create these specialists.
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Effects of Turning City Population into Specialists

§ When a city increases its population, it first seeks to employ that new population working the land around the city. (See Cities.) If any land spaces are yet unworked, the city puts the new civilian on the space it thinks will do the most good. A city can work up to 20 spaces - fewer if the city contains deserts or peaks in its City Radius. If you turn one of those working populations into a specialist, it no longer works the land. It still must eat, however, so the city's remaining working population must provide enough food for everybody. If not, the city will begin to starve. As a general rule, therefore, cities with more food will be able to create more specialists; cities that are food-poor will need all of their citizens to work the land just to prevent starvation.
§ Once a city is working all available land, it automatically turns any additional population into specialists (keep in mind this usually will not take place until very late in the game!). It attempts to create the most useful specialist available; if no other slots are open, it creates a citizen specialist. You can also manually create specialists yourself by removing citizens from working the land (see below). When a city is about to grow past the level of Happiness that it can support, it is often a good idea to turn some of the population into specialists and halt growth rather than let the city increase in size and produce useless unhappy citizens.
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Specialists and Great People

§ In addition to their other functions described below, specialists increase a city's generation of "Great People Points" by +3 each. Specialists also help determine what kind of great person the city will generate. See Great People for more details.
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How to Create a Specialist

§ You can create a specialist on the city screen. The six types are visible on the right-hand edge of the screen. If a specialist type is grayed-out, you cannot build one. If a specialist is in full color, however, you can: click on the plus (+) sign next to the specialist you want to create. If you want to remove a specialist, click on the minus (-) sign. Creating a specialist removes one of your population points from working a tile in the City Radius.
§ In order to manually select which tile to remove, first click on the tile that you want removed (the white circle around it should disappear). This creates a Citizen specialist. Then click on the plus (+) sign next to the specialist you want to employ, and the Citizen specialist will be replaced with the one you desire.
§ Note that some Wonders automatically give you one or more specialists of a specific type; you can't remove or repurpose them at all. Some wonders and civics may also provide you with a free specialist in each city; in this case, you can choose which specialist to employ in each city, but cannot remove the specialist altogether.
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Specialist Types

§ Engineer
§ Engineers increase a city's production by +2. They increase the city's great person generation rate by +3. They increase the chance that the city will generate a Great Engineer. Forges, Factories, and similar industrial buildings are needed to create Engineers.
§ Merchant
§ Merchants increase gold by +3. They increase the city's great person generation rate by +3. They increase the chance that the city will generate a Great Merchant. Markets, Banks, and similar commercial buildings are needed to create Merchants.
§ Scientist
§ Scientists increase a city's research rate by +3. They increase the city's great person generation rate by +3. They increase the chance that the city will generate a Great Scientist. Libraries, Universities, and similar research institutions are needed to create Scientists.
§ Artist
§ Artists increase a city's gold by +1, and its culture by +4. They increase the city's great person generation rate by +3. They increase the chance that the city will generate a Great Artist. Theatres and other centers of the arts are needed to create Artists.
§ Priest
§ Priests increase a city's commerce and production by +1 each. They increase the city's great person generation rate by +3. They increase the chance that the city will generate a Great Prophet. Temples, Cathedrals, and other religious buildings are needed to create Priests.
§  Citizen
§ Citizens increase a city's production by +1. They do not provide great person generation points, nor do they affect what kind of great person the city generates. Citizens require the construction of no buildings or wonders, and an unlimited number can always be employed. However, it is rarely worthwhile to create large numbers of Citizen specialists!
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Wonders and Civics

§ Many wonders and civics can increase the power of specialists even further, with a variety of different effects.
§ Increased Great Person Points
§ Several different wonders and civics increase the rate at which specialists create Great People. The Parthenon wonder increases the production of great person points by 50% in all cities, and the National Epic national wonder increases the rate by 100% in the city in which it is built. The Pacifism civic also increases great person generation by 100% in all cities.
§ Other Effects
§ Other effects include increasing the output of the specialists themselves. For example, the Angkor Wat wonder adds +1 production to all Priest specialists, and the Sistine Chapel adds +2 culture to all specialists. The Representation civic also adds +3 research to all specialists. Since all of these effects are cumulative, specialists can become very powerful if enough attention is paid to them.
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