In a previous issue of "The Behavior Analyst," the authors discussed the ambiguities that surround the distinction between positive and negative reinforcement. Seven distinguished behavior analysts commented on their article. The authors believe that this dialogue represented a constructive step toward clarification of an important concept within behavior analysis. Most notably, the discussion showed how difficult it is to arrive at a set of rules that can identify a reinforcer as positive or negative. Since then, the journal has received two more thoughtful contributions that appear in this issue. The authors' responses to Nakajima and Staats are presented.