Amicarbazone is a triazolinone herbicide with potential for controlling annual bluegrass and other weeds in seashore paspalum. Field experiments were conducted in the summer of 2011 and 2012 at Griffin, GA, to evaluate bermudagrass and seashore paspalum growth inhibition and injury following amicarbazone applications. Amicarbazone was applied to actively growing ‘Tifway’ bermudagrass and ‘Sea Isle 1’ seashore paspalum fairways at 0, 123, 246, 492, 738, or 984 g a.i. ha^-1. From regression analysis, amicarbazone rate required to injure bermudagrass 20% (I₂₀) measured 606 g ha^-1 at 1 WAT, but I₂₀ measured 221 g ha^-1 for seashore paspalum. At 2 WAT, I₂₀ and amicarbazone rate required for 20% clipping reduction (CR₂₀) measured >984 g ha^-1 for bermudagrass, while seashore paspalum measured 289 and 468 g ha^-1, respectively. Similarly, I₂₀ and CR₂₀ values measured >984 g ha^-1 for bermudagrass at 4 WAT, while I₂₀ and CR₂₀ values for seashore paspalum measured 509 and <123 g ha^-1, respectively. Overall, bermudagrass has relatively more tolerance than seashore paspalum, but amicarbazone may be safely applied at labeled use rates to seashore paspalum during active growth.