Abstract-This paper introduces Tournament Particle Swarm Optimization (PSO) as a method to optimize weights of game tree evaluation functions in a competitive environment using Particle Swarm Optimization. This method makes use of tournaments to ensure a fair evaluation of the performance of particles in the swarm, relative to that of other particles. The empirical work presented compares the performance of different tournament methods that can be applied to the Tournament PSO, with application to Checkers.