Based upon studies between 2001 and 2010 and the continued presence of adult shrimp including gravid females, Palaemon macrodactylus (Oriental Shrimp) is established in the estuarine waters of New York City. In summer 2010, we sampled a 1000-m² area of the East River and found that P. macrodactylus represented 4.3% of the total shrimp population, and 15.2% of the Palaemonidae (84.8% consisted of the native species Palaemonetes vulgaris [Common Grass Shrimp]). In 2001/2002, P. macrodactylus comprised 4.2% of all palaemonids, suggesting an increase in the past decade of non-native relative to native palaemonids. While not yet appearing to be “invasive” based upon population size, the feeding habits and reproductive biology of P. macrodactylus suggest that future interactions with native shrimp may occur. A key to regional shrimp is presented.