1) The context or circumstance in which an environment-behavior relationship occurs. The event changes the strengths of stimuli and responses involved in an environment-behavior interaction.

2) Stimulus events (or contexts), including complex antecedent conditions, events and stimulus response interactions, that exert general control over other stimulus-response interactions. Setting events may precede and/or overlap with other discrete stimulus-response (SD - R) relationships (e.g., noisy surroundings could influence adversely the interaction between a work assignment and a student's performance).