A one-name study is a project researching a specific surname, as opposed to a particular pedigree (ancestors of one person) or descendancy (descendants of one person or couple). Some people who research a specific surname may restrict their research geographically and chronologically, perhaps to one country and time period, while others may collect all occurrences world-wide for all time.
A one-name study is not limited to persons who are related biologically. Studies may have a number of family trees which have no link with each other.
Findings from a one-name study are useful to genealogists. Onomasticians, who study the etymology, meaning and geographic origin of names, also draw on the macro perspective provided by a one-name study.
Scope
Many people conducting family history, genealogical or onomastic research may conduct a one-name study of a surname in a given period or locality quite informally.
A full one-name study can be daunting, particularly if the surname is very common. Conversely, a rare surname can be difficult to trace. Since such studies are usually conducted by individuals as a pastime, they are generally feasible only when a surname is not used by more than a couple of thousand contemporary people, so that the total historical data-set is numbered in the low tens of thousands. Where a surname is used by hundreds of thousands, or millions of people, it would be practically impossible to differentiate these persons using national-index data alone.
In some cultures, one-name studies are impossible, since hereditary surnames are not used at all or in the case of names such as Singh may represent religious practice rather than an ancestry. Since a majority of human societies use patronymic surnames, one-name studies generally focus on male succession and ignore family relationships through marriage.
Some researchers are satisfied to collect all information and group it geographically, approximately representing the different family groups. Others attempt to reconstruct lineages.
In most one-name studies, a united lineage will not be discovered, but broad perspectives can be achieved, giving clues to name origins and migrations. Many researchers are motivated to go beyond the one-name-study stage and to compile fully researched, single-family histories of some of the families they discover.
Methods
Accessibility of the data required for a one-name study varies from country to country. Where civil registration indexes are open to public search, they may not be online or gathered in the national capital, but are scattered through the states, as in Australia, or towns, as in France and the United States. In many countries, such as Germany, civil registration and census data are regarded as a state prerogative: vital data are only available to the persons concerned and 19th-century census returns are not available at all.
One-name studies in the United States have become more feasible than they were, thanks to the increased availability of online indexes to 19th-century and early-20th-century censuses.
More limited one-name studies can be conducted using other national indexes including: telephone and address directories registers of wills or deceased estates electoral rolls land possession records military service indexes
One-name studies are generally rounded out with a miscellany of information drawn from national bibliographies, archival catalogues, patent databases, reports of law cases, tax lists, newspaper indexes and web searches. A one-name researcher may also report on the linguistic origins of the surname and its use in place names and corporate names.
UK surnames
Civil registration indexes of births, marriages and deaths in England and Wales (for the period from 1837), Scotland (from 1855) and Northern Ireland (from 1865 and Protestant marriages from 1845) are in the public domain, and anyone may apply to see the details of any birth, marriage or death. For the period before civil registration, in principle back to 1538 in England and Wales and 1533 in Scotland, parish registers have recorded birth and/or baptisms, marriages and deaths and/or burials. These are also freely available, although the survival of such registers is less likely as we reach back to the earliest dates of this period.