A feature of the Northern Iroquoian languages is their especially rich inventory of particles. This paper is concerned with one particle in the Cayuga language which has a widespread distribution and performs a broad range of apparently unrelated functions. The particle ne:' is commonly .translated as 'it is/that is', 'this' or ' that'. In other instances it is translated as predominant stress, or is simply omitted in the translation. The particle can occur in almost any syntactic or semantic environment, but it is not obligatory in any context. The various functions that have been suggested in the literature include indication of declarative mood and assertion, marking of emphasis, focus or contrast, and expression of predicative and deictic force. I argue that the particle ne:' can be described successfully if its distribution is considered from a wider perspective, taking into account discourse structure and variation in scope. Its analysis as a focus marker can account for the variety of apparently unrelated functions. The analysis is based on a detailed study of the particle' s distribution in spoken language using a database of five Cayuga texts by four different speakers, including three narratives, one procedural text and a children 's version of a ceremonial text.