- Microsystem: Refers to the institutions and groups that most immediately and directly impact the child’s development including: family, school, religious institutions, neighborhood, and peers.
- Mesosystem: Consists of interconnections between the microsystems, for example between the family and teachers or between the child’s peers and the family.
- Exosystem: Involves links between social settings that do not involve the child. For example, a child’s experience at home may be influenced by their parent’s experiences at work. A parent might receive a promotion that requires more travel, which in turn increases conflict with the other parent resulting in changes in their patterns of interaction with the child.
- Macrosystem: Describes the overarching culture that influences the developing child, as well as the microsystems and mesosystems embedded in those cultures. Cultural contexts can differ based on geographic location, socioeconomic status, poverty, and ethnicity. Members of a cultural group often share a common identity, heritage, and values. Macrosystems evolve across time and from generation to generation.
- Chronosystem: Consists of the pattern of environmental events and transitions over the life course, as well as changing socio-historical circumstances. For example, researchers have found that the negative effects of divorce on children often peak in the first year after the divorce. By two years after the divorce, family interaction is less chaotic and more stable. An example of changing sociohistorical circumstances is the increase in opportunities for women to pursue a career during the last thirty years.
Per this theoretical construction, each system contains roles, norms and rules which may shape psychological development. For example, an inner-city family faces many challenges which an affluent family in a gated community does not, and vice versa. The inner-city family is more likely to experience environmental hardships, like crime and squalor. On the other hand, the sheltered family is more likely to lack the nurturing support of extended family.
Since its publication in 1979, Bronfenbrenner’s major statement of this theory, The Ecology of Human Development  has had widespread influence on the way psychologists and others approach the study of human beings and their environments. As a result of his groundbreaking work in human ecology, these environments — from the family to economic and political structures — have come to be viewed as part of the life course from childhood through adulthood.
Bronfenbrenner’s work provides one of the foundational elements of the ecological counseling perspective, as espoused by Robert K. Conyne, Ellen Cook, and the University of Cincinnati Counseling Program.
There are many different theories related to human development. Human ecology theory emphasizes environmental factors as central to development