The Guild of One-Name Studies is the world's leading organisation for one-name studies. A one-name study is a project researching facts about a surname and all the people who have held it, as opposed to a particular pedigree (the ancestors of one person) or descendancy (the descendants of one person or couple).

The Guild is a charitable organisation dedicated to promoting the public understanding of one-name studies and the preservation and accessibility of the resultant information. Founded in 1979, the Guild now has over 2000 members spread across the world, studying over 7500 individual surnames.

The Guild brings together those with an interest in one-name studies and other forms of surname study (such as DNA projects). Many members register a surname so as to embark on a Guild-recognised one-name study and coordinate world-wide activity in studying the surname. Only one person may register a specific surname, but membership of the Guild is open to all with an interest in surname studies, and is not restricted to those who wish to register a name.