Black Grama (Bouteloua eriopoda) is a long-lived keystone primary producer across much of semi-arid southwestern North America. Though the ecology of this grass is relatively well studied, the potential effects of climate change on the species and ecosystem are more poorly understood. We examined size distribution and seed production of B. eriopoda following nine years of ongoing monsoon rainfall manipulation treatments. This Long Term Ecological Research (LTER) experiment is designed to imitate monsoon pulse precipitation patterns predicted by climate change models at Sevilleta National Wildlife Refuge, NM. Demographic measurements were collected in mid-June before the monsoon growing season began. Spikelets were collected once B. eriopoda florets went to seed in mid to late September. We found significantly higher mean tussock volume and height in plots with added precipitation compared to ambient control plots. Greater height was correlated with higher spikelet mass and average number of spikelets per inflorescence in long pulse treatment plots. This indicates an increase in reproductive fitness accompanying increased survival with less frequent, more intense rainfall. These findings shed light on how semiarid ecosystems may respond to shifting precipitation pulses in the Southwest with regards to a changing climate.