The functions of an American Sign Language response were experimentally evaluated with a young boy diagnosed with autism. A functional analysis procedure based on that reported by Lerman et al. (2005) was used to evaluate whether the target sign response would occur under mand, tact, mimetic, or control conditions. The target sign was observed most often in the mand and mimetic test conditions, very seldom in the tact test condition, and never in the control condition. These results support those reported by Lerman et al. and extend previous research by evaluating a non-vocal verbal response using a brief multi-element arrangement with a single control condition. The implications for language assessment and suggestions for future research are discussed.