In Japan, in the context of increasing demands from society, empirical knowledge is being accumulated on approaches to psychological support for people who have experienced an unexpected event, such as a natural disaster or accident. However, there are still no definitions of states of psychological crisis, and the methods of providing emotional support remain uncategorized, making it difficult to say that any fundamental ideas are shared among the clinical psychologists and others in the psychology field who provide this support. This situation may actually be inviting confusion in the places where the support is required. This paper traces the changes in the concept of crisis, reviews the literature that has been published up until now in Japan that has reported on crisis intervention and psychological support practices, and attempts to classify the criteria for determining states of psychological crisis and the appropriate support activities. The concept of crisis has been broadened and applied to communities as well as to individuals. Susceptibility to falling into a state of crisis depends on the adaptation abilities and stress tolerance of both individuals and communities. It is especially difficult for a community to recover independently when the seriousness of the situation goes beyond a certain level and many of its members fall into a state of crisis. In such cases, external support that promotes the self-healing capabilities of the community will be required. From the review of psychological support activities in Japan, it was found that the concept of crisis has been expanded, and, at the same time, the target of support has broadened from individuals to communities. Furthermore, in the case of the Great East Japan Earthquake, support was provided in a systematic and planned manner in order to prevent a disorderly flood of support. From the above, it can be said that a state of psychological crisis is a situation in which agents ranging from individuals to large groups of people can lose their psychological “homeostasis” and become mentally confused. One criterion for support for states of psychological crisis is whether or not the community needs support, and one focus is how many people there are requiring support, while another focus is the distribution of the people requiring support, whether they are localized or spread over a wide area. Based on this, it is possible to classify the levels of psychologically critical situations according to the scale of the support subjects and the degree of necessity of assist to supporters. Both of these measures were used to compose the axes of a plane model. The first through fourth quadrants were large support subjects and high degrees of necessity of assistance to the supporters, large support subjects and low degrees of necessity to assistance to the supporters, small support subjects and low degrees of necessity of assistance to the supporters, and small support subjects and high degrees of necessity to assistance to the supporters. These were defined as “large-scale / wide-range,” “large-scale / limitedrange,” “small-scale / limited-range,” and “small-scale / wide-range,” respectively. Then, the psychological support methods provided at the status levels of psychological crisis were organized. Consequently, it was speculated that systematic and planned support, psycho-education, network-type support and emergency support are provided in the “large-scale / wide-range,” “large-scale / limited-range,” “smallscale / limited-range,” and “small-scale / wide-range,” respectively.