Fallout 3 primary statistics

Overview
The minimum for each primary statistic is 1 and the maximum is 10. These boundaries can never be broken, even with bonuses or maluses, although the game keeps track of further increases internally. For example, if someone has 10 Agility and then finds the bobblehead for it, the Agility still stays at 10, but if there ever is a negative modifier - e.g. wearing Metal Armor (Ag -1) - the Agility will stay at 10, because the it was technically 11.

Each statistic directly modifies certain derived statistics. In addition, every skill is tied to a primary statistic. As a result, each point added to a primary statistic results in a bonus of 2 points to the associated skill(s). The only exception is Luck which only adds 1 point; in turn, all skills are affected by this stat. Some perks require certain minimum attribute values as well.

Increasing attributes
There are multiple ways to increase your attributes after character creation. They can be increased permanently by taking the Intense Training perk at level-up (which can be taken up to 10 times, at any level) or through various quest perks. Additionally, you can find a bobblehead for each attribute which increases its associated stat by 1 point (which makes raising an attribute to 10 at character creation a waste of points).

Attributes can also be increased temporarily by wearing certain armors and clothing, carrying certain items or using consumables.

With all ten Intense Training, the Night Person perk, the seven S.P.E.C.I.A.L. bobbleheads, the Lucky Shades, Three Dog's Head Wrap, Vance's Longcoat, the Lucky 8 Ball, and the Ant Sight/Might perk, it is possible to raise your total S.P.E.C.I.A.L. points to 68, compared to the 40 you start with; that's very close to maxing it out at 70.

If you have the Broken Steel add-on you can raise all of your S.P.E.C.I.A.L. to 10 with only one perk if you get the Almost Perfect perk before getting any of the S.P.E.C.I.A.L. bobbleheads.

For information on increasing specific attributes, please refer to the article for the respective attribute or to Fallout 3 stat-raising items.

Changes from previous Fallout games
Players who are accustomed to the rigid attribute and skill mechanics of the previous games may be happy to know that the new systems in Fallout 3 are much more flexible and allow for more changes during a character's development. For instance, tagging a skill no longer increases the rate of a skill's development, but skills gain their maximum effectiveness (and cap out) at 100. Additionally, while the Gifted trait (along with all traits) has disappeared, primary attributes are simultaneously less important and easier to acquire as your character grows.

Players who played the previous two games should also keep in mind that the SPECIAL system in Fallout 3 is much more forgiving when compared to the first two games: Low ability scores penalize the player less, while high ability scores do not grant as much of a benefit. Where in the first two games lowering a SPECIAL stat to 3 or lower could be a risky move regardless of your character type, characters in Fallout 3 can get away with SPECIAL scores of 1 in particular stats. For example, a character with 1 intelligence will find most character interaction in the first two games impossible, while in the 3rd you simply sacrifice a few Intelligence dependent conversation options and some skill points.