The major stage theories are the Psychoanalytic theory, behaviorism theory and Cognitive theory.

Ecological systems theory proposed by Urie Bronfenbrenner and dynamic systems theory are examples of developmental theories that are not stage theories. They emphasize the interactions between individuals and their environment, as well as the continuous and dynamic nature of development over time.

recurring-phase theories and sequential-stage theories

Patricia H. Miller has written:

'Theories of developmental psychology' -- subject(s): Human Development, Philosophy, Psychological Theory, Developmental psychology, Child psychology

'Theories of developmental psychology' -- subject(s): Child psychology, Developmental psychology, Philosophy

the developmental stage of cyclophyllidians in a hydatid cyst