The Japanese sentence-final particles, ne, yo and yone have proved notoriously difficult to explain and are especially challenging for second language users. This book investigates the role of the particles in talk-in-interaction with the aim of providing a comprehensive understanding that accounts for their pragmatic properties and sequential functions and that provides a sound basis for second language pedagogy. This study starts by setting up an original particle function hypothesis based on the figure/ground gestalt, and then tests its validity empirically with unmarked, marked and native/non-native talk-in-interaction data. The analysis illustrates not only expectable but also unexpected or strategic use of particles, as well as the problems posed for native speakers by non-native speakers whose use of particles is idiosyncratic. The study demonstrates that the proposed hypothesis is capable of accounting for all the uses of particles in the extensive and varied data set examined.