Society for Creative Anachronism
The Society for Creative Anachronism (SCA) is an historical recreation group with many similarities to Amtgard. Whereas Amtgard allows fantasy themes, the SCA focuses on exclusively historical study with no fantasy elements.
Combat in the SCA falls under two types: armored combat, which utilizes non-paddded rattan weapons and stringent armor standards, and rapier combat, a predecessor to modern fencing which uses rapiers, schlagers, and daggers (dulled and safety-tipped) with whole-body protection requirements and fencing masks or full helmets. The transition from SCA combat to Amtgard combat may be difficult for Society members as headshots are accepted and even expected in SCA combat.
While Amtgard is setup as a game, the SCA considers itself a historical society, not a LARP. However, there are many things Amtgard borrows from the SCA, starting with organization into local chapters such as shires and baronies under the umbrella of various kingdoms. No SCA groups are considered freeholds; they all fall under a specific kingdom which covers a specific regional area (generally contiguious, though some spread across multiple countries).
Apart from combat, the SCA is known for stressing a high degree of historical detail and research of the Middle Ages. Most participants in the SCA prefer to focus on building a generally historical culture without obsession over exacting detail, though some (colloquially known as "authenticity mavens") strive to active extreme accuracy and tend to critique those who do not meet their standards. In many instances, things that would be considered acceptable by Amtgard standards (basic garb, armor, names, heraldry, etc) would not be satisfactory in the SCA as they would not have plausibly been found in the Middle Ages. Golden City All-Stars tunics are an example of garb that would not meet minimum standards (though the basic shape without the modern sports embellishment might be acceptable).
Amtgard and the SCA share many participants and some individuals will transition from one group to the other depending on their personal preference. In some areas, there has been contention between the two groups. For example, in the Society, boffer weapons are used near-exclusively for youth combat and in some instances for practice or newcomer use.