殖民是將無主地轉化為殖民地的過程。它可以為任何希望成為列強的國家提供一些重要的好處：
《黑暗之心》中的殖民
在《黑暗之心》擴展包中，殖民是一項頗為複雜的內容。為了增長成為殖民帝國的潛力，你的國家需要一支強大的海軍和正確的科技，使得你能夠擴張到那些不適宜居住的地區。
機制
殖民分為三個步驟。
探險
要殖民一個省份，該省份必須在你的國家所能及的範圍內，並達到或超過你的國家的最低生活條件。只要目標省份離最近的海軍基地足夠近，或者與一個已經被控制的省份相鄰，目標省份就在殖民範圍之內（毗鄰一個衛星國也計入）。一個國家的最低生活條件受到其發現的科技的影響。
派遣一支探險隊需要消耗100點殖民力量，但如果目標省份毗鄰一個已經被控制的省份，則只需要80點。
探險隊派出後，必須等待一段時間才能對殖民地作出下一步行動。如果沒有其他國家在該地區進行殖民行動，殖民地可以直接變成保護國，只需付出一點點額外的殖民力量成本。然而，如果其他國家加入了競爭，這就變成了一場競賽，兩個國家將不斷升級他們的遠征隊，直到其中一方從競賽中撤出他們的殖民力量並承認失敗。
如果一場殖民競賽持續太久，它最終將引發一場危機。要想知道這場競賽有多接近危機，請查看地區視圖上的彩色進度條。
殖民省份/保護國
當一個列強或次強的遠征隊沒有受到另一個國家的競爭（可能是因為所有其他競爭對手都退出了），或者當一個國家比最近的競爭對手多投資了三個等級的遠征隊時，就可以建立保護國。
殖民地的維持成本比保護國高，但它們為國家提供了更多的稅收，並且國家可以從中徵召軍隊。然而，工廠不能在殖民地建造。
當一個開化國家通過「索要租借地」或「建立保護國」（儘管名稱如此，後者實際上創造了殖民地）的宣戰理由從未開化國家征服了一個地區時，也會產生殖民地。注意，即使目標地區已經是獲得它的國家的核心，它仍然會變成殖民地而不是本土（這種情況很少見，比如
South Africa收復他們在
Zulu的核心時）。
開化國家可以通過「陽光下的土地」的宣戰理由從另一個國家奪取殖民地。
州
將殖民地轉變為成熟的州需要在殖民地擁有至少1%的已接受文化
官僚人口。轉變為州需要消耗殖民力量（遊戲中顯示如此，但是實際上州不會占用任何殖民力量，因此它只是要求你的可用殖民力量達到一定數量，而不會實際消耗任何殖民力量，反而還會因不再有殖民地而增加殖民力量）。
殖民力量
殖民力量可以通過如下途徑獲得：
- +100來自「後納爾遜時代軍事思想」科技。這項加成通常作為所有列強、次強的基礎殖民力量。
- +30來自每個在核心領土上建造的海軍基地
- +20來自每個在核心領土上升級的海軍基地額外等級
- 海軍中的戰鬥艦隻（如果海軍數量超過了補給上限，超出部分的艦隻會減少殖民力量）：
| 級別 | 殖民力量 | 補給需求 | 每1點補給需求 產生的殖民力量 |
|---|---|---|---|
| 護衛艦 | 2 | 1 | 2 |
| 風帆戰列艦 | 5 | 2 | 2.5 |
| 破交艦 | 8 | 3 | 2.6 |
| 鐵甲艦 | 12 | 3 | 4 |
| 低舷鐵甲艦 | 10 | 3 | 3.3 |
| 巡洋艦 | 16 | 20 | 0.8 |
| 戰列艦 | 15 | 50 | 0.3 |
| 無畏艦 | 22 | 60 | 0.36 |
護衛艦、風帆戰列艦和破交艦可以用於在早期遊戲中獲取殖民力量，但應當在情況允許時轉變為更有效率的鐵甲艦或低舷鐵甲艦。鐵甲艦是最有效率的艦種，每1點補給需求產生4點殖民力量。但是，鐵甲艦相當昂貴，建造時間也長，並且不能在海外建造。因此，它們只適用於那些擁有許多本土海軍基地和充足的準備時間的國家。那些本土海軍基地很少或準備時間不足的國家應該把重點放在建造低舷鐵甲艦上。
巡洋艦、戰列艦和無畏艦的出現時間太晚了，對殖民競賽幫助不大，而且也是迄今為止效率最低的艦種。
殖民力量用於在殖民競賽中投資，以及將保護國轉變為殖民地。如果一個國家有足夠的可用殖民力量，並且一個殖民地滿足轉變為州的條件，那麼他們就可以把該殖民地併入自己的國家。這將釋放更多的殖民力量，允許他們發展新的殖民地。
然而，整合一個殖民地所需的可用殖民力量隨着距離的增加而增加，甚至可以輕易地超過一個偉大帝國的潛在殖民力量。如果一個國家希望殖民更多的土地，他們可以釋放一個相鄰的殖民地成為自治領。這可以通過「政治」界面上的「釋放」選項卡來完成，與釋放衛星國的方式相同。
生活條件與科技
所有國家在遊戲開始時的最低生活條件都是35。雖然有幾個地區可以在遊戲早期就殖民，但大多數潛在的殖民地並不是那麼宜居。
有三項發明可以降低一個國家的最低生活條件。他們是：
瘧疾預防藥物在研究藥品後每月有2%的概率被發現，降低5點最低生活條件。
開化使命和殖民談判的條件更為複雜：它們的發現概率並不取決於自身的前提科技，而是由任意列強或鄰國擁有此發明而增加10%，和該國擁有某項更為後期的科技而增加25%。
具體來說，開化使命需要三項1850年開啟的科技之一：
而殖民談判需要三項1870年開啟的科技之一：
研究任何一種後期科技所帶來增益，都超過了列強和鄰國已經擁有這項科技的增益之和。
一般來說，如果玩家是第一個獲得殖民談判的玩家，並因此能夠殖民，其他大國將很快由鄰國增益或列強增益而跟進。這導致了19世紀70年代的殖民熱潮，尤其是在非洲，那裡大多數空曠的省份的生命等級都是10或15（歷史上，對非洲的爭奪始於1881年）。任何一個在1880年之前還沒有研究後膛槍的國家都可能會錯過機會，發現整個非洲都已經被殖民了。
Strategy
Early colonization (before 1870)
A handful of provinces have life rating 35 and so their states can be colonized in 1836:
- Alberta and British Columbia: Occasionally the
USA grabs the parts of BC that the 
United Kingdom doesn't already have, but otherwise only the United Kingdom is in a position to colonize them, and almost always does so. - Oklahoma, Colorado, Oregon and Washington: These are contested between the USA and
Mexico. They often go to war over them (when the USA takes the "Manifest Destiny" decision giving them cores on all of the continental US), and the USA usually wins. - Sakhalin: An island north of
Japan. Both 
Russia and Japan have cores, but Japan starts uncivilized and so can't colonize for at least a couple of decades, leaving Russia free to grab it after building a Pacific naval base. - Turkmenia: Initially inaccessible to any power, Russia can colonize by conquering Khivan Uzbekia; the Ottomans would have to conquer two states from Persia.
- Bornu: Being in the interior of west Africa, colonizing this requires conquering part of
Sokoto. This is a strategically important location that can give the player a big advantage during later colonization. - Lourenço Marques, Zambezia (not to be confused with Zambezi) and Mocambique (sic): Inaccessible to anyone but Portugal, they will start colonizing these from day 1.
- South Madagascar:
Portugal and 
France can try for Comoros and Mayotte (despite the state name these islands are north of Madagascar), and the United Kingdom can build a naval base in the Seychelles or Mauritius; anyone else probably won't have range.
A few more have life rating 30 and can be colonized with only Prophylaxis against Malaria. With luck, a quickly westernizing uncivilized country may be able to take some of these, but they are still mostly restricted to an exclusive club.
- Manitoba and Saskatchewan: Only the United Kingdom has access here, unless the USA manages to seize BC.
- Alor, Sunda Islands: Bordering the Netherlands' and Portugal's colonial possessions in Indonesia, this can also be picked up by
Spain. The United Kingdom will have to build a naval base first. - Darfur: Even the AI will conquer Dongola from
Egypt to get access to both this and a coastal province for a port. Only Fasher in the south has life rating 30, but this allows colonizing the entire state. - Amhara and Oromia: These states border (and are partially owned by) Ethiopia, who can get them immediately if they somehow become a secondary power in time; anyone else will have to conquer land from Ethiopia.
- South Georgia: Usually taken by the United Kingdom, this island, historically only ever used as a whaling station and never permanently inhabited, can also be taken by
Brazil or 
Argentina if they become a secondary power at the right time. - South Island and North Island, New Zealand: Only the United Kingdom has anywhere near the range to get these.
The following can be colonized from 1850, once the country has Mission to Civilize:
- East Angola and South Angola: More African states that only Portugal will have access to. These are also the only provinces that can be colonized with only Mission to Civilize and without Prophylaxis against Malaria, but you will want Medicine anyway.
- Interior of Australia: In 1836 the United Kingdom has already colonized the entire coast of Australia, so only they get access here.
- Northwest Territories: Part of Canada, only the United Kingdom is likely to have access.
- Etorofu and Shumshu (the Kuril Islands): Like Sakhalin, both Japan and Russia have cores here; unlike Sakhalin, Japan stands a chance of colonizing them if they're quick to westernize and get colonization tech.
The Scramble for Africa (1870s)
All other uncolonized provinces, including almost all of Africa, have life rating 15 or 10 and can only be colonized with both Mission to Civilize and Colonial Negotiations. Since most powers who have researched Breech-Loaded Rifles get Colonial Negotiations at almost the same time, there is a rush of colonization activity soon after any great power has discovered it. Those with life rating 10 also require Prophylaxis against Malaria, but any savvy power will have it anyway. A more in depth guide can be read here: Guide for Scramble of Africa
In the base game and in A House Divided
Mechanics
To colonize an uncolonized area, the following requirements must be met:
- Have a country status of at least secondary power (i.e. civilized and rank 16 or better);
- A naval base in range OR share a land border with the target colony;
- Have the technology to tolerate the life-rating of the area.
All nations start with a life-rating minimum of 35. Most colonial areas only have a life-rating of 15. However, you can lower your minimum allowed life-rating through research:
- Industry tech: Prophylaxis Against Malaria (Medicine) (1836)
- Culture tech: Nationalism & Imperialism (1850)
- Army tech: Machine Guns (1870)
Once all the requirements are met, select the "Colonize" national focus on your target to began the colonization process. Since most uncolonized areas are out of reach until both Machine Guns and Nationalism & Imperialism are researched, large scale colonization will not begin until 1870 at least. However for a colonial power to succeed, it would be important to prepare naval bases and rack up focus points in the years prior.
Conversion to a full state
To convert a colony to a full state it is necessary to have 1% bureaucrats in the colony state in your accepted culture. In general, having this number of bureaucrats is achievable once an acceptable culture makes up approximately 5% of the population of the colony. There is a greyed out button next to the national focus icon that tells you your progress, when that number is reached, you may press the button to convert the colony into a state. A colony may only be converted to a state when you are not at war. Note that due to these requirements, the vast majority of colonies in the game will never be able to convert to states.
Factories can only be created in states, so creating states can help a country's industry.