This article discusses the marketer and customer co‐creation process within the context of bilateral contingencies. Bilateral contingencies occur when the marketers' behavior is reinforced (and/or punished) by the customers' behavior, whereas the behavior of the customers is reinforced (and/or punished) by the marketers' actions. Using the example of the LEGO community, we discuss how the marketers in the organization can respond to behaviors resulting from co‐creational customer–customer exchanges. This paper fills the knowledge gap by presenting a behavior analysis framework (theory of the marketing firm) for the empirical measurement of the co‐creation process.