This paper summarizes the institutional approach to culture which Yamagishi and colleagues have developed, and present critical findings supporting the approach. Human as well as non-human individuals create, maintain, and alter through their actions the very environment to which they adapt. That is, they are niche constructors. One important aspect of human niches is what I call “social institutions.” Humans collectively create, maintain, and alter social environment – constraints and incentives for their behavior to which they individually adapt. A social institution is a stable set of such constraints and incentives created and maintained by individuals’ behaviors. The institutional approach to culture analyzes culture-specific psychology and behavior as an adaptation to social institution or the set of constraints and incentives individuals face. The support for this approach is found in five aspects. First, individuals’ private values and preferences do not always coincide with their perceptions of what others value and prefer. Second, behavior is more strongly related to the perceived consensus than private beliefs and values. Third, people anticipate others’ responses based on the perceived consensus. Fourth, the use of default strategies such as the not-offend-others strategy is based on the (often implicitly) anticipated responses of others. Finally, the use of default strategies such as the not-offend-others strategy collectively creates the institution in which incentives (people’s actual behaviors and beliefs about the behaviors) encourage people to follow the strategies.