Behavioral contrast has been interpreted as a function of either (1) the reduction of frequency of reinforcement in one component of a multiple schedule or (2) the suppression of responses in one component regardless of reinforcement frequency. These explanations are discussed in terms of their adequacy in accounting for several recent experimental results. Two alternative explanations are considered. First, contrast is interpreted as a function of the relative summation of excitatory and inhibitory effects of stimuli. Second, contrast is discussed as a possible function of a switch from a response-reinforcer contingency to a stimulus-reinforcer contingency as seen in auto-pecking. Both avenues are considered promising in terms of accounting for behavioral contrast.