Kentucky bluegrass (Poa pratensis L.) is being developed for possible commercial release with transgenic traits, but the use of this technology raises risk assessment questions as P. pratensis is perennial, often apomictic, competitive in many habitats, and hybridizes with other Poa. To better understand the potential environmental impact of hybrids of other Poa with a transgenic P. pratensis, we measured reproductive fitness traits in F₁ and F₂ transgenic hybrid progeny, backcrosses to the parents of those hybrids, and intercrosses with other hybrids of the same species. Thus far, we have identified that most hybrids have less than or equal characteristics compared to their parents.  Seed quantity is one characteristic where hybrids produced a greater number of seeds than their parents.  Two hybrids produced more seeds than both of the parents, and one hybrid from a P. interior line produced more seeds than the maternal parent but less than the paternal parent.  The same two hybrids also produced a greater amount of spikelets per plant than their parents, but one produced fewer spikelets than its maternal line.  A hybrid from a P. pratensis line produced more spikelets per plant than its parents, but fewer florets per spikelets.  Many other comparisons are currently being observed, such as the germination rate compared to the viability of the pollen.  The evaluation includes the percent apomixis of the hybrid, percent glyphosate resistant progeny, pollen viability, seed production, and various physical morphological characteristics.