For most children with autism spectrum disorder (ASD), manding for information is an important skill that must be systematically taught. Although previous studies have evaluated interventions for teaching other mands for information, to date no studies have demonstrated effective procedures for teaching the mand "why?" The purpose of the present study was to teach 3 children with ASD to mand "why?" under relevant establishing operation conditions in 3 distinct scenarios. A trial-unique multiple-exemplar procedure was used to promote generalization and increase the value of information provided across trials. All 3 participants learned to mand "why?" in all 3 scenarios within a mean of 18 sessions (range 14-21 sessions), demonstrated generalization to novel stimuli and settings, and maintained this skill over time. Social validity for the intervention had an overall mean of 5.88 (range 1-7).