Zen's challenge for behavior analysis is to explain a repertoire that renders analysis itself meaningless-a result following not from scientific or philosophical arguments but rather from a unique verbal history generated by Zen's methods. Untying Zen's verbal knots suggests how meditation's and koans' effects on verbal behavior contribute to Enlightenment and Samādhi. The concept of stimulus singularity is introduced to account for why, within Zen's frame of reference, its methods can be studied but its primary outcomes (e.g., Samādhi and Satori) cannot be described in any conventional sense.