Seed quality of forage grasses is influenced by seed density, storage conditions, age of seed, and endophyte infection status.  We used eight seed lots of tall fescue (three cultivars, with natural endophytes, endophyte-free, or novel endophyte) in these experiments to test the effect of seed density.  Seed lots were separated into light and heavy fractions by using a cylinder air column to produce eight seed density classes, plus the original seed lot for nine classes per entry.  Thousand seed weight values were determined, and confirmed the success of our separation technique.  Three runs of four replications of plots consisting of 25 seeds of each entry were seeded in greenhouse experiments to determine seedling mass at six weeks after planting.  Seedling mass was recorded on a per-plant basis to account for differences in germination rates.  Early germination counts as well as lab germination tests indicated significant differences among weight classes in speed of germination as well as seedling vigor.