Victory conditions can be set at the galaxy setup screen.

There are four ways in which you can win in Galactic Civilizations II:

1. Conquest Victory: Wipe out all other major races in order to achieve this. Note that you can achieve this victory without conquering any of the minor races, even if they happen to control more than one planet. (However, since you are already in the warring mood, why leave them alone?). At higher levels of difficult (especially at suicidal), doing this alone may not be possible. Setting alliances aside, a cunning way of doing this is to pay certain stronger civilizations to go to war with the weaker ones in an attempt to weaken the civilizations involved.
2. Diplomatic Victory: Form an alliance with all surviving major races in order to win this victory. This is a lot harder than it sounds, as some races will most likely never ally with you simply because of who you are. Unfortunately, some races really don't understand what it means to be friendly with everyone so you'll have to "bring them some friendship" in the form of warships and troop transports. One might have to start early and establish good relations with potential allies instead of having to wait till the mid or late portions of the game, as diplomatic relations are cumulative and a sudden attempt to sway them in your favor may not be able to overcome their distrust of you.
3. Influence Victory: Have your civilization's influence dominate at least 75% of the galaxy. When you accomplish this task a message will appear, stating that if you maintain your influence dominance for 10 weeks you will win. You'll need to make room for a fair amount of cultural improvements and projects to get this accomplished. In addition, you cannot be at war with any of the other major races before this victory is possible. In addition, dominating at least 75% of the galaxy's influence may not be possible without a hold on ann already sizable percentage of the galaxy's planets. Thus for games involving higher levels of difficulty, war may be inevitable, both defensively and offensively.
4. Technological Victory: There are five technologies at the very far-end of the tech tree that must be researched before being able to win the Technology Victory:

• Deeper Knowledge >> Galactic Understanding >> Near Omniscience >> Beyond Mortality >> Technology Victory

Note that when another rival civilization has researched the penultimate technology (Beyond Mortality, though in TA this might differ for certain civilizations), a warning will be given to the player of this attempt to score a technological victory. Given the exigency of this message, it would be important to annihilate or thwart (perhaps through espionage) that civilization's attempt as soon as possible, but in many cases the warning would arrive too belatedly for the player to do anything about it. In TA, researching prerequisite technologies prior to Technological Victory grants a research bonus (+X%), hence increasing the incentive to research some of the earlier technologies like Deeper Knowledge, which would otherwise be completely useless if the player does not wish to pursue a Technological Victory.

1. Ascension Victory: In the Twilight of the Arnor, controlling a certain number of Ascension crystals for a limited period of time will allow that particular race to ascend and win an Ascension Victory. The maximum number of crystals that are available at anytime (as checked by use of the Map Editor) is 5, though some maps might have fewer. Each crystal a race controls will generate one "Ascension Point" per turn, and victory is achieved once 1000 points have been amassed. Losing a crystal doesn't lose you any points, so one can simply build a new base on top of the crystal and continue trying to ascend.

Some of the scenarios and campaign missions may have alternate victory conditions.

NOTE: It is generally considered to be a score multiplier of 1.0 for a Tech Victory, 1.2 for an Alliance (Diplomatic) Victory, 1.4 for an Influence (Cultural) Victory, and 2.0 for a Conquest (Military) Victory. This may be of interest to Metaverse players. Source: GalCiv Forum Thread