CR practitioners rely on historical sources and archaeology for their rituals and beliefs, including offerings to spirits and deities.

[2][3] The study of mythology and folklore was part of modern paganism from its inception, and while many groups focussed on witchcraft, some sought to revive pre-Christian religions.

[4] During the 1980s, some of these reacted against the eclecticism and the focus on the "spirit" of the ancient religions in favor of "reconstructing what can be known from the extant historical record".

[3] In both the United States and Britain, Celtic reconstructionism became an umbrella term encompassing several sub-traditions,[7] which vary in particular in the geographic region whose religion they aim to reconstruct, such as British,[10] Irish,[11] Scottish, or Welsh.

[10][14] While the ancient Celtic religions were largely subsumed by Christianity,[15] many religious traditions have survived in the form of folklore, mythology, songs, and prayers.

[19] Feedback from scholars and experienced practitioners is sought before a new practice is accepted as a valid part of a reconstructed tradition.

[22] Some practice divination; ogham is a favored method, as are traditional customs such as the taking of omens from the shapes of clouds or the behavior of birds and animals.

[27] Some took part in the protests against the proposed destruction of archaeological sites around the Hill of Tara in the course of construction of the M3 motorway in Ireland, as well as performing a coordinated ritual of protection.

[32] Within reconstructionism, there are varying degrees of emphasis on accuracy as opposed to what best reflects the essence of the religion in a modern context.

[33] There has been cross-pollination between Neo-druid and Celtic reconstructionist groups, and there is significant crossover of membership between the two movements, but the two have largely differing goals and methodologies.

[5] However, some Neo-druid groups (notably Ár nDraíocht Féin (ADF), the Order of Bards, Ovates and Druids (OBOD), and the Henge of Keltria) have adopted similar methodologies of reconstruction at least some of the time.