By treating the surface of toner particles with submicrometer particulate addenda, it has been possible to reduce the size of the toner from approximately 12 μm to 8μm. Presumably, this is because the particulates separate the toner particles from the photoconductor, thereby facilitating transfer. However, in the area of digital electrophotography, where images frequently comprise halftone dots, the cohesiveness of the toner stacks may affect the final image quality. This paper discusses the effect on transfer of surface treated toners, with the surface treatment concentration varying between 0 and 2% by weight of toner. In essence, it was found that, while transfer efficiency increased with increasing silica concentration, resolution decreased and dot structure after transfer was degraded. Toner adhesion measurements, performed using an ultracentrifuge, were found to correlate well with the transfer efficiency measurements and suggest that the observed transfer behavior may be interpreted in terms of toner-to-photoconductor adhesion and interparticle cohesion effects.