Samian: the resource Samian pottery (terra sigillata) is one of the best-quality data sources available for research in the Roman period. Its wide distribution, standardised typology and comparatively close dating combine to make this artefact class particularly amenable to analytical approaches. Examination of its archaeological occurrence reveals dimensions of patterning that provide a unique and exciting window upon the character of society and cultural practice during the Roman era. Earlier phases of the project conducted in the late 1990s, funded by English Heritage, included a pilot survey which had verified the reliability and utility of the project methodologies, and a research synthesis which brought new light to bear on this familiar material type of the Roman era. The findings arising from these stages have been published previously (Willis 1997; 1998). The results of this project, as presented here, demonstrate how study of this material resource can contribute, and in a number of areas transform, our knowledge of the period. The project has had a strong synthesising and analytical imperative, with the intention of bringing together existing knowledge of samian to ensure fuller use of this valuable asset. The potential has hitherto been somewhat 'hidden', being compartmentalised within site reports and other publications, there having been only limited opportunities in the past for the distillation of the archaeology of samian beyond dating. (Samian is a key indicator of chronology in the early and mid Roman period in North-West Europe and will remain so. A developing archaeological awareness of the era, however, will be strongly enhanced through examination of other facets of samian data). Samian distribution and group composition is here shown to be a source of valuable information, which may be effectively harnessed to shed light upon a series of aspects of Roman Britain, with resonance beyond the province of Britannia. Project aims and results This study was directed towards making the best use of samian evidence as a key resource for exploring a range of questions in Roman archaeology. The study collates a large body of data and applies hitherto under-utilised methods in an endeavour to extract archaeological information from this material, particularly in the key areas of dating, the social distribution of samian and cultural practice. One avenue in respect of dating has been to explore the extent to which trends in the composition of groups of samian, in terms of forms present, may be used as a guide towards establishing the date of a group without having to depend heavily upon the dating of stamps and diagnostic decorated sherds, which may be comparatively rare. It is intended that the resulting guide, presented here, proves to be an accessible and straightforward tool for the non-specialist user. The project, moreover, aimed to move beyond the essential role of samian in providing 'dates', to exploit its evident high potential for elucidating aspects of cultural and economic life during the Roman era. Findings from analyses undertaken in a series of such areas are published here. The research, indeed, sheds light on a wide variety of aspects of Roman Britain. The nature, for instance, of samian supply to Britain is examined. It was intended that the project dataset would provide a flexible tool which readers themselves were able to access so that they may pursue their own questions (view database online), and/or with which they may compare their own samian groups, by reference to a corpus of data collected from a range of sites across Britain covering all appropriate periods (go to the ADS archive to download spreadsheets). In one highly significant finding, the collected data demonstrate how the character of site samian assemblages is strongly related to site type, status, function, exchange connections and identity. Previous work for the project has indicated that the incidence of samian is often patterned. The present study further defines the extent to which there are 'normal patterns' (or parameters) of samian occurrence by time, region and site type. A framework guide to the 'normal patterns' identified by the project and with which specific site assemblages and stratified groups can be compared is presented as a summary in section 13.1.2 of the article. While focusing on samian, the project has aimed to locate samian within its broader context. Hence project objectives and discussion of findings are integrated with the present general research aims in the study of the Roman era in western Europe. Throughout the study it was intended that the work be directed and relevant to themes in the archaeological investigation of the period, rather than be just specific to samian studies: this is appropriate since samian is part of a wider nuanced record of life in Roman Britain. Samian is here considered in a wide range of fields; it is striking how richly patterned and illuminating this evidence proves to be.