Studying nonnative species soon after their introduction is critical to understanding their risk of becoming widely invasive and determining effective methods of control. I conducted laboratory and field experiments on the Rasberry crazy ant (Paratrechina sp. nr. pubens), which was introduced to Pasadena, TX in 2002 and has since been spreading rapidly. These experiments focused on intraspecific aggression, as well as individual and colony-level interactions between crazy ants and red imported fire ants (Solenopsis invicta), which are dominant in the crazy ant's introduced range. Crazy ants displayed no intraspecific aggression. In individual aggressive encounters with fire ants, crazy ants had higher mortality than fire ants, but in colony-level clashes, crazy ants had less mortality and better control of food resources. These findings suggest that crazy ant abundance is key to their competitive success, and fire ants may provide biotic resistance to crazy ants in some areas.